JPH03237002A - Reactor for fuel cell - Google Patents

Abstract

PURPOSE:To efficiently operate the reactor when the reactor is started and the load of a fuel cell is reduced and to make the reactor compact by using a coaxial multiple-tube structure and surrounding the inner desulfurizer with the outer carbon monoxide converter. CONSTITUTION:Natural gas (raw gas) is supplied from the raw gas inlet nozzle 15 at the lower end of the inner cylinder 2, and allowed to ascend in the inner cylinder 2 and then descend in an annular passage 11. The sulfur in the raw gas is hydrogenated to hydrogen sulfide by a hydrogenation desulfurization catalyst 6 in the passage 11, and the hydrogen sulfide is adsorbed on the desulfurization adsorbent 7. The desulfurized raw gas is discharged from a desulfurized gas outlet nozzle 19 and sent to a reformer. The reformed gas consisting essentially of hydrogen is adjusted to a specified temp. by a heat exchanger and supplied to a reactor 1 from a reformed gas inlet nozzle 20. The reformed gas is allowed to descend in an annular passage 13 and then ascend in an annular passage 12, the concn. of carbon monoxide in the reformed gas is reduced by a shift reaction catalyst 8, and then the reformed gas is discharged from a reformed gas outlet nozzle 21 and used as the fuel gas for a fuel cell.

Description

[Detailed Description of the Invention] [Industrial Fields of Application] The present invention is directed to a method for reforming natural gas into fuel for fuel cells.
Regarding a reaction device for post-processing natural gas into an optimal form for use in fuel cells, in detail, it has the functions of both desulfurization of natural gas before reforming and carbon monoxide conversion after reforming, and The present invention relates to a fuel cell reaction device that can be operated efficiently both during startup and when the load on the fuel cell is reduced, and which can be made more compact.

[Prior Art] A fuel cell is a device that generates electrical energy through an electrochemical reaction between hydrogen supplied to the anode (fuel electrode) side and oxygen supplied to the cathode (air electrode) side. The above hydrogen is produced by mixing natural gas with water vapor,
This is passed through a catalyst layer to produce hydrogen-rich reformed gas (
A combustible gas containing hydrogen as a main component and carbon monoxide, carbon dioxide, methane, etc. is used, while the oxygen is produced by introducing air. Examples of devices for reforming natural gas include JP-A-53-78992, JP-A-53-79766, and JP-A-5B.
-! No. 10862, No. 58-63783, Special Publication No. 1983
-7538 etc. are known.

By the way, if the reformed gas contains a large amount of carbon monoxide, the generated voltage will decrease depending on the concentration, so it is necessary to use a carbon monoxide transformer to convert the carbon monoxide in the reformed gas as fuel. Is it necessary to place it upstream of the battery? Such devices have been proposed, for example, in Japanese Patent Laid-Open Nos. 63-229138 and 1-188407.

On the other hand, the above-mentioned reformer often uses a catalyst containing nickel as a catalyst, and this catalyst has a sulfur component as a poisonous substance. Is it necessary to remove the sulfur component contained in the gas using a desulfurizer before reforming?

[Problems to be solved by the invention] Common problems in devices related to fuel cells include:
■Compactness, ■Shorter temperature rise time at startup, ■Simplification of control, ■Reduction of heat loss, etc. However, the carbon monoxide shift converters that have been proposed so far generally require a long time to raise the temperature at startup, and the reaction temperature is set between the catalyst activation temperature (180℃ or higher) and the catalyst deterioration prevention temperature. The reality is that little consideration has been given to appropriate control during the temperature range (below 260°C).

Moreover, until now, the desulfurizer and the carbon monoxide shift converter were generally arranged separately, which was insufficient in terms of (1) and (2) above.

The present invention was made to solve these technical problems, and its purpose is to have both the functions of a desulfurizer and a carbon monoxide transformer, and to provide a In either case, it can be operated efficiently,
Moreover, it is an object of the present invention to provide a fuel cell reaction device that can be made compact.

[Means for Solving the Problems] The fuel cell reactor of the present invention, which is distantly related to the above object, includes a desulfurizer that desulfurizes natural gas before reforming it as a fuel for fuel cells, and a It has a structure that integrates a carbon monoxide transformer that transforms carbon monoxide in the reformed gas after reforming, and has a coaxial multi-tube structure, so that the inner desulfurizer is surrounded by the outer carbon monoxide transformer. The main point lies in the fact that it is structured as follows.

[Operations and Examples] The configuration and operation effects of the present invention will be explained in more detail below based on the drawings of the examples, but the following examples are not intended to limit the present invention, and are designed with the spirit of the above and below in mind. Any modifications are included within the technical scope of the present invention.

FIG. 1 is a cross-sectional explanatory diagram showing one embodiment of the reaction apparatus of the present invention, in which 1 is the reaction apparatus, 2 is the inner cylinder, 3 is the middle cylinder, 4 is the outer cylinder, and 5 is the reaction apparatus.
6 is a heat insulating material that constitutes the reactor body, 6 is a hydrodesulfurization catalyst,
7 is a desulfurization adsorbent, 8 is a shift reaction catalyst, and 9 is an electric heater.

The reactor 1 has a coaxial multiple tube structure in which an inner tube 2, a middle tube 3, an outer tube 4, and a heat insulating material 5 are arranged with a gap between them, and is formed between the inner tube 2 and the middle tube 3. The annular passage 11 is filled with the hydrodesulfurization catalyst 6 and the desulfurization adsorbent 7, and
The shift reaction catalyst 8 is filled in the annular passage 12 formed between the outer cylinder 4 and the heat insulating material 5. Said inner cylinder 2, middle cylinder 3
A desulfurizer is configured by the hydrodesulfurization catalyst 6 and the desulfurization adsorbent 7, and a carbon monoxide shift converter is configured by the inner cylinder 3, outer cylinder 4, heat insulating material 5, and shift reaction catalyst 8, and the reaction device 1 is constructed in such a way that an inner desulfurizer is surrounded by an outer carbon monoxide transformer. The annular passage 13 formed by the inner cylinder 3 and the outer cylinder 4 and the annular passage 11 are separated from each other by the inner cylinder 3, but are configured to be able to transfer heat to each other.

Natural gas (raw material gas) is supplied from a material gas port 15 at the lower end of the inner cylinder 2, rises inside the inner cylinder 2, and then descends through the annular passage 11. Sulfur in the raw material gas is hydrogenated to hydrogen sulfide by the hydrodesulfurization catalyst 6 in the annular passage 11, and the hydrogen sulfide is adsorbed by the desulfurization adsorbent 7. In the figure, 17 is a perforated plate-shaped catalyst holder, and 18a and 18b are perforated plate-shaped catalyst receivers.

Further, as the desulfurization adsorbent 7, zinc oxide is exemplified.

The desulfurized raw material gas is taken out from the desulfurization gas outlet nozzle 19 and sent to the reformer A (see FIG. 5 below).

On the other hand, the reformed gas whose main component is hydrogen gas is transferred to the heat exchanger D (
After the temperature is adjusted by the process (see FIG. 5 below), the reformed scum is supplied into the reactor 1 from the population nozzle 20. The reformed scum descends in the annular passage 13 and then rises in the annular passage 12, where the concentration of carbon monoxide in the reformed gas is reduced by the shift reaction catalyst 8, and then the reformed gas exits from the reformed gas outlet nozzle. 2
1 and used as fuel for fuel cells.

The electric heater 9 heats the shift reaction catalyst 8 at startup, and at startup, high-temperature inert gas (for example, nitrogen) or steam is introduced from the nozzle 15, 20 to heat the entire reactor 1. .

Since the reactor 1 of the present invention integrates a desulfurizer and a carbon monoxide shift converter, the outer surface area can be reduced, external heat radiation can be suppressed, and it is advantageous in terms of heat insulation construction cost. be.

At startup, high-temperature inert gas, etc. flows through the nozzle 15 as mentioned above.
．． However, according to the device of the present invention, the heat at that time spreads throughout the device, preventing local areas from becoming abnormally high, allowing considerably high temperature gas to flow, and increasing the temperature. The heating time can be shortened. Further, the thickness of the catalyst packed bed can be made thin in a layered manner, and heat can be easily transferred to the entire packed bed even when heated by a heater, and from this point of view as well, the temperature rising time can be shortened.

On the other hand, during normal operation, even if there are slight fluctuations in the temperature of the waste introduced from nozzles 15, 20, etc., or even if reaction heat is generated downstream of the shift conversion catalyst layer, the overall gas and equipment components are Heat is transferred, temperature leveling is easily achieved, the allowable range of gas population temperature can be expanded, and control can be simplified.

The configuration of the reaction apparatus 1 according to the present invention is not limited to that shown in FIG.
Of course, the reformed gas flow path may be in the opposite direction. For example, as shown in FIG. 2, the inner cylinder 2a is filled with a hydrodesulfurization catalyst 6 and a desulfurization adsorbent 7, The gas flow may be configured such that it ascends through the annular passage 11 and then descends within the inner tube 2a. Alternatively, a heater may be placed at a suitable location within the feed gas or reformed gas introduction flow path to accelerate the temperature rise of the hydrodesulfurization catalyst 6 and the carbon monoxide shift catalyst 7 at the time of startup.

FIG. 3 is a cross-sectional explanatory diagram showing still another embodiment of the present invention, and since the basic configuration is similar to that shown in FIG. 1, corresponding parts are designated by the same reference numerals. Avoid duplicate explanations. Since a fuel cell is a power generation facility, it is preferable that it can be operated without consuming as much electrical energy as possible, and there are many problems as a power generation facility if a large amount of electric power is required to start the power generation facility.

Desulfurization is an exothermic reaction, but since the sulfur content in natural gas is small, there is no temperature rise and no cooling is required. There is a temperature rise of about ℃, and cooling is required. Therefore, in the embodiment shown in FIG. 3, in order to be able to sufficiently cope with fluctuations in the temperature of the raw material gas and reformed gas,
The structure is such that the temperature of the carbon monoxide shift catalyst can be set within an appropriate temperature range using saturated hot water without using an electric heater. That is, as shown in FIG. 3, a spiral flexible pipe 25 is provided so as to pass through the shift reaction catalyst 8 in the annular passage 12, and saturated hot water of about 170 to 200° C. is supplied from a hot water inlet nozzle 26 to the flexible pipe. 25, the catalyst 8 is cooled by the hot water, and the temperature of the catalyst 8 is maintained in the range of 180 to 260 °C, which is the general reaction temperature of carbon monoxide reaction,
The hot water is taken out through the outlet nozzle 27. On the other hand, the desulfurizer operates at a slightly higher temperature than the carbon monoxide shift converter, but since the desulfurizer is surrounded by the carbon monoxide shift converter, the temperature does not fluctuate significantly, allowing stable operation. be done.

In the embodiment shown in FIG. 3, a nitrogen supply pipe 30 is provided outside the inner cylinder 2, and the nitrogen supply pipe 30 is provided on the outside of the inner cylinder 2, as the main part (circular part IV) is shown in FIG. A configuration is shown in which high temperature nitrogen is blown out from an outlet 31. This is to raise the temperature of the desulfurization catalyst 6 to 180 to 300 degrees Celsius during startup, and the temperature rise is achieved by supplying high-temperature nitrogen of about 300 degrees Celsius from the supply nozzle 32 and blowing it onto the desulfurization catalyst from the nitrogen outlet 31. Let's do it. - When starting up the Kerr carbon oxide shift converter, saturated hot water is introduced from the hot water outlet nozzle 27, and the catalyst 7 is heated by its latent heat of condensation, and condensed water is discharged from the hot water inlet nozzle 26.

By adopting such a configuration, startup can be performed in a short time without using an electric heater, and temperature control can also be achieved with higher precision.

Although the embodiment shown in FIG. 3 shows a configuration in which hot water is passed through the flexible pipe 25, the means for supplying hot water is not limited to that shown in the figure. It is also possible to adopt a configuration in which a water jacket is provided or the inner wall surface of the heat insulating material is made of plate coils.

The reaction apparatus of the present invention is incorporated into a system as shown in FIG. 5, for example. FIG. 5 is a conceptual diagram showing a water-cooled fuel equipment system for using the device of the present invention, where A is a reformer, B is a fuel cell main body, C is a steam/water separator, D and E are heat exchangers, F
is a cooling water circulation pump, and G is a nitrogen circulation pump. H indicates a starting boiler, and other than typical constituent parts are omitted. Note that FIG. 5 is based on the case where the reaction apparatus 1 shown in FIG. 3 is used.

The outline of the system will be explained below.

At startup, reformer A burns natural gas.

Further, nitrogen is circulated to the reforming side of the reformer A by a nitrogen circulation blower G. When the temperature of the flue gas coming out of the reformer A begins to rise, nitrogen is heated in the heat exchanger E and is blown into the hydrodesulfurization catalyst 6 of the reactor 1. The temperature of the water will rise. Nitrogen leaving the reactor 1 enters the reforming side of the reformer A, where it is heated by a burner, so its temperature is raised again. The nitrogen circulates toward the nitrogen circulation blower G in front of the fuel electrode of the fuel cell main body B while raising the temperature of the shift reaction catalyst 8 of the heat exchanger 1 reactor 2.

1. In response to the startup of reformer A, startup boiler H is also started, and steam is generated from this boiler in a few minutes. This steam is introduced into the steam separator C, and then into the flexible pipe 25 of the reactor 1, and heats the shift reaction catalyst 8 from the outside. When the temperature of the shift reaction catalyst 8 reaches the maximum temperature of the circulating nitrogen due to heating by circulating nitrogen and steam, steam is also introduced into the reforming line. That is, the steam generated in the startup boiler H passes through a steam separator C, is heated in a heat exchanger, and is combined with circulating nitrogen before the reformer A. Put it on the quality side.

After the nitrogen/steam mixture gas is heated by the burner of reformer A, it is sent to the piping and heat exchanger after reformer A.

The piping 9 after the heat exchanger, the reactor 1, and the piping after the reactor 1 are heated. At this time, the shift reaction catalyst 8, which is concerned about being the slowest in temperature rise, has been preheated by the flexible pipe 25, so not only can the temperature rise time of the entire reforming system be significantly shortened, but also the shift reaction catalyst 8 There is no chance of condensed water leaking.

During normal operation, natural gas flows toward the heat exchanger. That is, natural gas is heated to a temperature suitable for the desulfurization reaction in the heat exchanger after a small amount of reforming residue mainly composed of hydrogen is added for hydrodesulfurization before the heat exchanger. , reactor] into the hydrogenation reaction catalyst 6. The natural gas desulfurized in the reactor 1 is mixed with steam coming from the steam separator C and then introduced into the reforming side of the reformer A. Note that during normal operation, the nitrogen circulation boiler G and the startup boiler H are stopped. At this time, steam is generated by the heat generated in the fuel cell body B. Natural gas is reformed in reformer A into reformed gas containing hydrogen as a main component. The heat required for this reaction can be supplemented by burning the fuel cell waste fuel in a burner. The reformed gas that exits the reformer A is cooled to the temperature required for the carbon monoxide shift reaction in a heat exchanger, and then heated to the carbon monoxide shift catalyst in the reactor 1 (the shift reaction catalyst 8). ) is introduced within. Although the reaction here is exothermic, it is cooled by saturated hot water coming from the steam separator C. The saturated hot water evaporates in the corrugated pipe 25 and returns to the steam separator C through natural circulation (thermosyphon type heat exchanger). In this way, reformed sludge suitable as fuel for fuel cells can be obtained. During normal operation, the temperature of the artificial gas in reactor 1 fluctuates due to load fluctuations. In particular, in reactor 1 shown in Figure 3, in addition to the desulfurizer being surrounded by a carbon oxide shift converter, the catalyst is Since the system uses a cooling configuration, optimal operation can be maintained without the need for complex temperature control.

[Effects of the Invention] As described above, the present invention has both the functions of a desulfurizer and a carbon monoxide transformer, and can operate efficiently both at startup and when reducing the load on the fuel cell. A reactor for fuel cells was realized that can be made more compact and can be made more compact.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional explanatory diagram showing one embodiment of the reaction apparatus of the present invention, FIG. 2 is a cross-sectional explanatory diagram showing another embodiment of the reaction apparatus 1,
FIG. 3 is an explanatory cross-sectional view showing still another embodiment of the present invention, FIG. 4 is an enlarged view showing the main part (■) of FIG. 3, and FIG. FIG. 2 is an explanatory diagram of a combustion battery equipment system. 1... Reactor 3... Middle tube 6... Hydrodesulfurization catalyst A... Reformer C... Steam-water separator 2... Inner tube 4... Outer tube 8...・Shift reaction catalyst B... fuel cell body, E... heat exchanger

Claims (2)

[Claims] (1) Consisting of an integrated configuration of a desulfurizer that desulfurizes natural gas before it is reformed as fuel for fuel cells, and a carbon monoxide shift converter that converts carbon monoxide in the reformed gas after reforming.
1. A reactor for a fuel cell, characterized in that it has a coaxial multi-tube structure, and is configured such that an inner desulfurizer is surrounded by an outer carbon monoxide transformer. (2) The method according to claim (1), characterized in that the desulfurization catalyst filled in the desulfurizer and the carbon monoxide shift catalyst filled in the carbon monoxide shift converter are configured to be heated. Reactor for fuel cells.