JPH01186565A - Fuel cell power generator - Google Patents

Abstract

PURPOSE:To prevent the concentration reduction of the carbon dioxide from a reformer by separately providing a cooling section for cooling the cathode of a fuel cell. CONSTITUTION:The city gas TG is desulfurization-processed by a desulfurizer then passes through a heat exchanger 20 and is guided into the cooling section 19 of a fuel cell 1. A catalyst is put in the cooling section 19, the city gas TG is reformed here, the heat of the cathode 2 of the fuel cell 1 is deprived by the heat absorbing reaction at the time of reformation, and the cooling action takes place. The gas going out from the cooling section 19 is guided into the reforming section 5a of a reformer 5 and reformed, it then passes through the heat exchanger 20 and fed to the anode 3 of the fuel cell 1, the gas discharged from the anode 3 is guided to the combustion chamber section 5b of the reformer 5.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a fuel cell power generation device used in the energy sector for directly converting the chemical energy of fuel into electrical energy.

[Prior art] Among the fuel cells proposed to date, for example,
A molten carbonate fuel cell uses an electrolyte plate (tile) in which a porous material is impregnated with molten carbonate as an electrolyte, and a cathode <r! It is sandwiched from both sides by the i elementary electrode) and the anode (fuel electrode), and by supplying oxidizing gas to the cathode side and supplying fuel gas to the anode side, electricity is generated by the potential difference generated between the cathode and the anode. In this case, one cell is made up of 1 cell, and each cell is laminated in multiple layers with a separator interposed in between.

In the power generation device using the above-mentioned molten carbonate fuel cell, it has been proposed to use natural gas, city gas, coal, etc. as the fuel gas.
When using natural gas as fuel, natural gas is reformed, when using city gas as fuel, city gas is reformed, and when using coal as fuel, coal is gasified and refined. .

As a fuel cell power generation system that uses a room temperature gas containing sulfur, such as city gas, as the fuel for a molten carbonate fuel cell, a configuration shown in FIG. 3 is known. That is, city gas G to be supplied to the anode 3 of the fuel cell 1 is introduced into the reformer 5 through line 4, reformed there, and supplied to the anode 3 through line 6, and the above-mentioned reformed gas A desulfurizer 7 for removing sulfur content from the gas is installed in the middle of the line 4 on the inlet side of the vessel 5, and natural gas preheaters (heat exchangers) 8 and 9 are connected to the desulfurizer 7. The gas discharged from the anode 3 is placed on the upstream and downstream sides of the natural gas preheater 9.8.
The gas is introduced into the combustion chamber of the reformer 5 after exchanging heat with the city gas TG that enters the reformer 5 while passing through the reformer 5 in this order. In addition, in order to supply oxidizing gas to the cathode 2 of the fuel cell, air A is compressed by a compressor 10 and then passed through an air preheater 11, a turbine 12, and an air preheater 13 to a line 1.
4 to the cathode 2, and part of it is supplied to the combustion chamber of the reformer 5 through a branch line 15,
The gas discharged from the cathode 2 is branched so that one side is discharged through the air preheater 13, the superheater 16, and the evaporator 17. superheated and supplied to the line 4;
The gas containing carbon dioxide discharged from the combustion chamber outlet of the reformer 5 is supplied to the cathode 2 together with the gas flowing through the line 14. . 18 is a compressor.

[Problems to be Solved by the Invention] However, in the conventional fuel cell power generation device described above, cooling is performed by flowing a large amount of air to the cathode 2 side for cooling the fuel cell 1. The gas containing CO2 that exits the reformer 5 and is supplied to the cathode 2 is
It will be mixed with a large amount of air introduced as a cooling gas and supplied to the cathode 2.
There was a problem that high power generation efficiency could not be obtained due to the low concentration of CO2.

Therefore, the present invention aims to prevent the concentration of carbon dioxide from the reformer from decreasing by reducing the amount of air mixed with the gas containing carbon dioxide that comes out of the reformer and is supplied to the cathode. It is.

[Means for Solving the Problems] In order to achieve the above object, the present invention supplies gas reformed in a reformer to seven nodes of a fuel cell, and supplies the gas discharged from the anode to the above-mentioned In a fuel cell power generation device in which air is introduced into the combustion chamber of the reformer, and air is mixed with the gas exiting the combustion chamber of the reformer and supplied to the cathode of the fuel cell. The configuration includes a cooling section for cooling the cathode.

[Function] Since the heat inside the cathode of the fuel cell can be removed by a separately provided cooling section, the amount of air as oxidizing gas supplied to the cathode can be reduced. This can prevent a decrease in the concentration of carbon dioxide gas supplied from the reformer to the cathode.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, in which one cell of a fuel cell 1 includes, in addition to a cathode 2 and an anode 3, a catalyst as a cooling section for removing heat within the cathode 2. A cooling section 19 is provided to reform the city gas gas G as a fuel gas, and the city gas gas G is connected to the desulfurizer 7.
After being desulfurized in the cooling section 1 through the heat exchanger 20
9, and 1G of city gas is introduced into the reforming section 5a of the reformer 5 after being reformed in advance in the cooling section 19, where the reformed gas is heated by the above-mentioned heat. The anode 3 line 22 of the fuel cell 1 via the exchanger 20
The gas discharged from the anode 3 is introduced into the combustion chamber 5b of the reformer 5.

In addition, in order to supply oxidizing gas to the cathode 2 of the fuel cell 1, air A is compressed by a compressor 10, and then divided into two lines, and the air A led to one line 14 is supplied to the cathode 2. At the same time, the air A branched to the other line 15 is introduced into the combustion chamber 5b of the reformer 5 after passing through the heat exchanger 23, and the air A branched into the other line 15 is introduced into the combustion chamber 5b of the reformer 5. is provided with an ejector 24 so that the gas containing carbon dioxide discharged from the combustion chamber portion 5b of the reformer 5 is drawn by the air passing through the ejector 24 and supplied to the cathode 2, and further, The gas discharged from the cathode 2 passes through the heat exchanger 23 to the evaporator 2.
5, the water H20 led to the evaporator 25 through the water softener 26 is evaporated, a part of the steam is merged into the line 21, and the rest is used for hot water supply, and the gas leaving the evaporator 25 is Let it lead you to the chimney.

In the conventional fuel cell power generation device shown in Fig. 3, city gas T
G is desulfurized and directly introduced into the reformer 5 for reforming, while a large amount of air is supplied to the cathode 2 as an oxidizing gas to cool the fuel cell. Now, to change this point, the city gas TG is desulfurized and then guided to the cooling section 19 of the fuel cell 1 to cool the fuel cell, so the amount of air supplied to the cathode 2 is reduced from the conventional method. can be reduced compared to That is, after the city gas TG is desulfurized by the desulfurizer 7 , it passes through the heat exchanger 20 and is first introduced into the cooling section 19 of the fuel cell 1 . A catalyst is placed in the cooling section 19 so that the city gas TG is reformed there, and an endothermic reaction during this reformation removes heat from the cathode 2 of the fuel cell 1, resulting in a cooling effect. It will be done. The gas exiting the cooling section 19 is then introduced into the reforming section 5a of the reformer 5, where it is reformed, and then supplied to the seven nodes 3 of the fuel cell 1 through the heat exchanger 20. The gas discharged from the anode 3 is in the combustion chamber 5b of the reformer 5.
be led to.

On the other hand, air A is compressed by the compressor 10 and then branched into two parts, one of which is supplied to the cathode 2 of the fuel cell 1 through the ejector 24 via the line 14. The gas containing carbon dioxide discharged from the chamber 5b is sucked into the airflow by the ejector 24 and supplied to the cathode 2.

At this time, the gas from the reformer 5 is sucked by the ejector 24 and supplied to the cathode 2, so gas containing carbon dioxide can be supplied to the cathode 2 without using a drive source, making it possible to achieve compactness. At the same time, the pressure difference between the anode 3 and cathode 2 can also be eliminated by the action of the ejector 24. The gas discharged from the cathode 2 exchanges heat with the air passing through the branched line 15 in the heat exchanger 23, and then is led to the evaporator 25, where the introduced water is evaporated.
Part of the steam is mixed with city gas TG for steam reforming.

In the present invention, since the cathode 2 is cooled by the cooling unit 19 of the fuel cell 1, there is no need to cool the cathode 2 by the air flow flowing toward the cathode 2, and the amount of air supplied to the cathode 2 can be reduced. The concentration of carbon dioxide gas supplied from the reformer 5 to the cathode 2 does not decrease accordingly.

Next, in the fuel cell power generation apparatus of the present invention, the reformer 5 is of a plate type, and the heat exchanger 20 is also of a plate type and housed together with the fuel cell stack in one pressure vessel 27 as shown in FIG. By stacking them and forming the line in an internal manifold type without flowing gas, it is possible to almost eliminate connecting piping, which has the advantage of making the whole compact.

Note that the present invention is not limited to the above-mentioned embodiments; for example, the cooling unit 19 may include a catalyst therein to reform city gas, and the heat of the cathode 2 may be absorbed by an endothermic reaction at this time. Although we have shown a case in which deprivation cooling is performed, as shown in an example in FIG. The cathode 2 may be cooled by flowing a large amount of air into the cooling unit 19 for cooling, and the amount of air supplied to the cathode 2 may be reduced accordingly. In this case, city gas T
G will be introduced into the reformer 5 after desulfurization.

[Effects of the Invention] As described above, according to the fuel cell power generation device of the present invention,
A cooling section is provided to cool the cathode of a fuel cell, and gas is passed through the cooling section to cool the cathode. By correcting the decrease in the concentration of carbon dioxide gas, it is possible to significantly reduce the air supply to the cathode side, preventing a decrease in the concentration of carbon dioxide gas due to mixing with air, and achieving high power generation efficiency. This can produce excellent effects.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing one embodiment of the fuel cell power generation device of the present invention, FIG. 2 is a system diagram showing another example of the present invention, and FIG. 3 is a system diagram of a conventional fuel cell power generation device. . DESCRIPTION OF SYMBOLS 1... Fuel cell, 2... Cathode, 3... Anode, 5... Reformer, 19... Cooling part, 24... Ejector, TG... Town gas, A... ·air. Figure 1

Claims (1)

[Claims] 1) The gas reformed by the reformer is supplied to the anode of the fuel cell, and the gas discharged from the anode is introduced into the combustion chamber of the reformer, and the combustion chamber of the reformer is In a fuel cell power generation device in which air is mixed with the gas emitted from the fuel cell and supplied to the cathode of the fuel cell, a cooling section is provided adjacent to the cathode of the fuel cell, and the cooling section cools the cathode. 1. A fuel cell power generation device, characterized in that the fuel cell power generation device is configured to introduce gas into a portion of the fuel cell.