JPS6180768A - fuel cell system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a fuel cell system in which carbon deposition at the anode is prevented, and particularly to a fuel cell system suitable for using coal gasified fuel or the like.

[Background of the invention]

Until now, the amount of fuel supplied to the anode chamber of a fuel cell was 1
Euell of 979 EPRI EM-1097 (::
ell power plant Integr
Ated SystemsEvaluation
As discussed in the technical literature, by adding a large amount of water to raw fuel, such as LNG, LPG, methanol, light oil such as naphtha, and coal, the operating conditions of the fuel cell, i.e., The gas composition was modified to make carbon precipitation less likely to occur under operating pressure and temperature.

However, even in fuel in such a state, it is difficult to say that carbon precipitation over time can be completely avoided.

Furthermore, the fuel flow rate obtained by adding a large amount of water to the raw fuel (i.e., making the steam carbon ratio (HIO/C molar ratio) several times larger than the theoretical limit value for non-carbon precipitation) and reforming it is comparable. As the fuel pipes, etc. become larger, not only does the entire system become larger, but the electrolyte is diluted by the large amount of H2O contained in the fuel, causing a voltage drop and reducing battery efficiency. It had the disadvantage of lowering the

[Purpose of the invention]

An object of the present invention is to provide a fuel cell system that can effectively prevent carbon deposition on the anode.

[Summary of the invention]

As a means of preventing carbon deposition at the anode of a fuel cell, the present invention provides a carbon precipitator that intentionally performs carbon deposition before the fuel enters the anode chamber, and prevents the carbon precipitated at the anode of the fuel cell. It was designed to be removed by a precipitator.

Here, a carbon precipitator is one that has at least the same amount of a substance that is active in the carbon precipitation reaction held in the anode of a fuel cell, and the fuel supplied to the anode chamber in the carbon precipitator comes into direct contact with this substance. However, it refers to equipment that can operate under conditions (pressure, temperature) that are likely to cause carbon deposition, including the operating conditions of a fuel cell. The structure, shape, etc. of the carbon precipitator are not limited to those shown in FIGS. 2 and 3.

[Embodiments of the invention]

Hereinafter, the embodiments of the present invention will be described with reference to a fuel cell system using coal gasified fuel, but the present invention can be similarly and easily applied to other fuels.

An embodiment of the present invention will be explained with reference to FIG. fuel cell 1
is constructed by stacking a cathode 3 and an anode 5 sandwiching an electrolyte 2, a cathode chamber 4 surrounding the cathode 3, and an anode chamber 6 surrounding the anode 5, and a carbon precipitator 7 and a heat exchanger are installed before the anode chamber 6. 8 and coal gasifier 9 are installed in this order to constitute a fuel cell system. The operation of this embodiment will be explained below. Raw fuel 10 (containing at least coal and an oxidizing agent) is introduced into coal gasifier 9 and gasified. The fuel gas 12 obtained from the coal gasifier 9 is cooled by exchanging heat with air 11 (or oxygen) in the heat exchanger 8, and activates the carbon precipitation reaction held in the anode 5 of the fuel cell 1. In the carbon precipitator 7 containing the same amount or more of the same substance as shown, the following Boudouard reaction 2 CO”C+ 002 + 38.2 kcal/m
Before the fuel gas 12 reaches the anode chamber 6, the carbon content precipitated at the anode 5 is removed by a carbon precipitator 7.
Precipitate within. In that case, for example, if the operating pressure in the carbon precipitator 7 is equal to the force in the anode chamber 6 of the fuel cell 1,
゛Tokitun8°“4°”°′4 reaction,! As is clear from the fact that is an exothermic reaction, the operating temperature in the carbon precipitator 7 is set below the inlet temperature of the anode chamber 6 of the fuel cell 1, and carbon precipitation occurs more easily in the carbon precipitator 7 than in the anode 5. Conditions maintained. As a result, the fuel gas 12 is supplied to the anode chamber 6 in the form of fuel gas 13 obtained by subjecting the fuel gas 12 to carbon precipitation treatment in the carbon precipitator 7, so that carbon precipitation is extremely difficult to occur on the anode 5 of the fuel cell 1. A fuel gas composition is realized. Thereafter, the fuel gas 13 passes through the anode chamber 6, becomes exhaust gas 14, and is discharged from the anode chamber 6. On the other hand, air 11 (or oxygen) heated by a heat exchanger 8 is supplied to the cathode chamber 4, and the exhaust gas 1
6 and is discharged from the cathode chamber 4. According to an embodiment of the present invention, it is possible to prevent carbon deposition at the anode of a fuel cell, thereby improving the life of the anode's catalytic activity and preventing clogging of the porous body constituting the anode. This has the effect of preventing electrical short circuits between the electrodes and improving the thermal efficiency of the fuel cell system because the gas supplied to the cathode chamber undergoes heat exchange and is heated within the system. Furthermore, since no H2O is used, dilution of the electrolyte in the fuel cell is reduced, and cell efficiency is maintained stably without increasing voltage drop.

FIG. 2 is a diagram showing the simplest structure of the carbon precipitator 7. As shown in FIG. The fuel gas 12 passes through a pipe 50 connected to the carbon precipitator 7 and comes into direct contact with a substance 52 that is active in the carbon deposition reaction and is held inside the carbon precipitator 7 (held at the anode of the fuel cell). Piping 5 connected to carbon precipitator 7
1, the fuel gas 13 undergoes carbon precipitation treatment and is discharged.

FIG. 3 shows another example of the structure of the carbon precipitator 7.

The configuration and operation will be described below. The fuel gas 12 passes through a pipe 50 connected to the carbon precipitator 7 and is guided into the carbon precipitator 7 . The carbon precipitator 7 also has an inner tube 57 having a double-pipe structure, and the upper part of the inner tube 57 is partitioned with at least the same amount of the same substance 52 as the substance 52 that is held in the anode of the fuel cell and shows activity in the carbon precipitation reaction. It is internalized by a plate 56. Inner tube 5
The lower part of 7 is hollow, and a cooling pipe 54 for flowing water 53 is arranged at the lowest part of the hollow. The tip 55 of the cooling tube 54 has a spray structure and is placed above the inner tube 57 filled with the substance 52 . When the fuel gas 12 enters the carbon precipitator 7 and a carbon deposition reaction is activated by the substance 52, carbon is deposited on the substance 52. In order to maintain the activity of the substance 52 covered with carbon deposition, water is sprayed from the tip 55 of the cooling pipe 54 provided in the inner tube 57 to wash and remove carbon on the surface of the substance 52. After spraying, the fuel gas is cooled by a cooling pipe 54 provided at the bottom of the inner pipe 57, and the condensate receiver is condensed and collected in a part 58 as water 59 containing carbon. 59 is processed as appropriate. On the other hand, the fuel gas 13 obtained by removing the precipitated carbon and the sprayed moisture and undergoing carbon precipitation treatment comes into contact with the outer wall of the cooling pipe 54, and then passes through the inner pipe 54.
7 and the outer tube of the carbon precipitator 7, the temperature is raised by heat exchange with the upper part of the inner tube 57, and the carbon precipitator 7 passes through a pipe 51 attached to the carbon precipitator 7 to move to the next stage. In this way, the performance of the carbon precipitator 7 is improved in that it can be used for a long time.

FIG. 4 shows another embodiment of the invention. Parts that are different from those in FIG. 1 will be explained. This embodiment is characterized in that two carbon precipitators 7 and 17 are installed in parallel. That is, the fuel gas 12 that has passed through the heat exchanger 8 first passes through the opened pulp 18, and then passes through the pulp 18, which is opened, to collect carbon containing the same amount or more of the same substance as the substance that is active in the carbon precipitation reaction held in the anode 5 of the fuel cell 1. The fuel gas 13 is subjected to a predetermined carbon precipitation treatment in the precipitator 7, and the pulp 19 is opened.
The fuel is introduced into the anode chamber 6 of the fuel cell 1 via . At this time, the pulp 20 installed before and after the carbon precipitator 17
and 21 are closed.

Thereafter, as the performance of the carbon precipitator 7 deteriorates, the carbon precipitator 17, which has the same performance as the initial carbon precipitator 7, is used in place of the carbon precipitator 7. Here, pulps 18 and 19
When the pulps 20 and 21 are closed, the pulps 20 and 21 are opened. That is, the fuel gas 12 passes through the heat exchanger 8, then the opened pulp 20, and then the carbon precipitator 177 and the predetermined carbon precipitator 1! The resulting fuel gas 13 is introduced into the anode chamber 6 of the fuel cell 1 via the opened pulp 19. In addition to the effects of the embodiment shown in FIG. 1, this embodiment has the carbon precipitators installed in parallel, so even if the performance of the carbon precipitators deteriorates, the
By switching to the other carbon precipitator, the fuel cell system can be operated stably and continuously for a long period of time. In addition, while the other carbon precipitator is operating, the performance of the carbon precipitator whose performance has decreased can be improved by replacing the filling material in the container or regenerating it using an oxidizing agent, carbon solvent, etc. The aim is to restore the fuel and reincorporate it into the fuel cell system, making it possible to use it for a long period of time.

The embodiment shown in FIG. 5 is different from the embodiment shown in FIG.
This figure shows an example of a system in which the temperature is increased by heat exchange with the fuel cell 1, and the temperature is increased and then supplied to the anode chamber 6 of the fuel cell 1. This is because the carbon precipitator 7 is required to have a larger carbon precipitation capacity than the steady state, and in addition, it is necessary to lower the temperature in order to further activate the Boudouard reaction. The fuel cell 13 is introduced for temperature control in order to raise the temperature of the anode chamber 6 to the inlet temperature of the anode chamber 6 of the fuel cell 1. In addition to the effects of the embodiment shown in FIG. 1, this embodiment has a heat exchanger installed next to the carbon precipitator to raise the temperature of the fuel gas. The stability of the battery system is further improved.

Figure 6 shows a fuel cell system in which the parts in Figure 4 that are different from Figure 1 and the parts in Figure 5 that are different from Figure 1 are combined and added to Figure 1. is the fourth
The effects of the embodiments shown in FIGS. and 5 are combined.

In the embodiment shown in FIG. 7, in addition to the embodiment shown in FIG. air 11
(or oxygen) to cool down the carbon precipitator 7.
After being introduced into the tank, the fuel gas 13 obtained by carbon precipitation is returned to the heat exchanger 25, heated to the inlet temperature of the anode chamber 6, and then supplied to the anode chamber 6. With this example, the first
In addition to the effects of the embodiment shown in FIG.
The heat 1' possessed by the direct fuel gas 12 from the coal gasifier 9, which is discharged at a relatively high temperature, is used to raise the temperature of the fuel gas 13 obtained by carbon precipitation from the carbon precipitator 7. This has the effect of further improving the thermal efficiency of the fuel cell system.

The embodiment shown in FIG. 8 is a fuel cell system that is the same as the embodiment shown in FIG. 4, with the addition of the parts shown in FIG.
The heat exchangers 25 and 8 through which the fuel gas 12 obtained from the coal gasifier [9] passes are arranged in series, and the next stage is the pulp 18, the carbon precipitator 7, and the pulp 9 arranged in series. Pulp 20, carbon precipitator 17, pulp 2
1 connected in parallel, the fuel gas 13 obtained by carbon precipitation from the carbon precipitator 7 (or 17) is heated by exchanging heat with the fuel gas 12 in the heat exchanger 25, and then transferred to the anode chamber 6. supplied to This embodiment combines the effects of the embodiments shown in FIGS. 4 and 7.

In the embodiment shown in FIG. 9, in addition to the embodiment shown in FIG. is washed and removed and discharged to the outside as water 59 containing carbon. In addition to the effects of the embodiment shown in FIG. 7, this embodiment extends the performance life of the carbon precipitator, making it possible to use it continuously over a long period of time.

In the embodiment shown in FIG. 10, in addition to the embodiment shown in FIG. Then, the carbon deposited on the surfaces of the substances provided for carbon deposition in the carbon precipitators 7 and 17 is washed and removed, and is discharged to the outside as water 59 containing carbon. In this embodiment, in addition to the effects of the embodiment shown in FIG. 8, even more stable performance of each carbon precipitator can be obtained, and
Continuous use becomes possible.

In the embodiment shown in FIG. 11, in addition to the embodiment shown in FIG.
,.

It is inserted between the heat exchanger 9 and the heat exchanger 25 and recycled. In addition to the effects of the embodiment shown in FIG. 9, this embodiment recycles and uses the exhaust gas 14 containing effective fuel that has not reacted in the anode 5 of the fuel cell 1, so that the tendency of carbon precipitation can be suppressed. The efficiency of the fuel cell system can be improved.

In the embodiment of FIG. 12, in addition to the embodiment of FIG. 10, the exhaust gas 14 from the anode chamber 6 is inserted between the coal gasifier #, 9 and the heat exchanger 25 and recycled. In addition to the effects of the embodiment shown in FIG. 10, this embodiment recycles and uses the exhaust gas 14 containing effective fuel that has not reacted in the anode 5 of the fuel cell 1, so that the tendency of carbon precipitation can be suppressed. The efficiency of the fuel cell system can be improved.

In addition to the embodiment shown in FIG. 11, the embodiment shown in FIG. 13 is configured so that a mixed liquid 59 of water discharged from the carbon precipitator 7 and precipitated carbon can be mixed with the raw fuel 10, so that water and carbon can be mixed together. Both the mixed liquid 59 and the raw fuel 10 are put into the coal gasifier 9, and a fuel gas 12 is obtained. This example is the 11th
In addition to the effects of the embodiment shown in the figure, since the water 53 used in the carbon precipitator 7 and the precipitated carbon are used as part of the raw fuel in the fuel cell system, the tendency of carbon precipitation can be suppressed, and the raw fuel consumption can be reduced.

In addition to the embodiment shown in FIG. 12, the embodiment shown in FIG. 14 can mix a mixed liquid 59 of water and precipitated carbon discharged from the carbon precipitator 7 or 17 with the raw fuel 10, so that water and carbon can be mixed. Both the mixed liquid 59 and the raw fuel 10 are put into the coal gasifier 9, and a fuel gas 12 is obtained. This embodiment has the advantage of the carbon precipitator 7 or 17 in addition to the effects of the embodiment of FIG.
Since the water used and the precipitated carbon are used as part of the raw fuel in the fuel cell system, it is possible to suppress the tendency of carbon precipitation and to reduce the consumption of raw fuel.

In addition, in any of the above embodiments, the coal gasifier 9
It is easy to imagine a system in which a fuel purification device such as desulfurization or denitrification is installed immediately after the denitrification. In addition, the carbon deposition devices 7 and 17 can be partially made of quartz or the like so that the state of carbon deposition inside them can be visually grasped.

〔Effect of the invention〕

According to the present invention, before the fuel supplied to the anode chamber of the fuel cell enters the anode chamber, a carbon precipitator containing at least the same amount of the same substance as the substance that is active in the carbon precipitation reaction held in the anode is provided. Therefore, carbon precipitation at the anode can be effectively prevented.

[Brief explanation of drawings]

1, 4 to 14 are views showing one embodiment of the present invention, and FIGS. 2 and 3 are sectional views showing an example of the structure of a carbon precipitator. 1...Fuel cell, 6...Anode chamber, 7.17...
- Carbon precipitator, 10... raw fuel.

Claims (1)

[Claims] 1. In a fuel cell consisting of an anode chamber surrounding an anode and a cathode chamber surrounding a cathode, before the fuel supplied to the anode chamber enters the anode chamber,
A fuel cell system characterized by being provided with a carbon precipitator for precipitating carbon.