JPH0689735A - Hybrid fuel cell power generation device - Google Patents

Abstract

PURPOSE:To use the energy of CO effectively by installing a fuel cell which converts the CO energy into electricity at the pre-stage of a phosphoric acid type fuel cell, wherein, however, the CO concentration of the fuel supplied to the phosphoric acid type fuel cell is reduced by means of denaturing of the CO. CONSTITUTION:A solid electrolyte type fuel cell 11 is installed at the rear stage of a modifier 3, and power generation is conducted using a fuel which consists of CO and hydrogen from the modifier 3, wherein the CO is converted into CO2 with the resultant CO concentration reduction, and the gas containing the residual hydrogen is cooled by a cooler 15 and supplied to the anode 7 of a phosphoric acid type fuel cell 6, and thus power generation takes place.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hybrid fuel cell power generator having a phosphoric acid fuel cell having a phosphoric acid electrolyte and a solid electrolyte fuel cell having a solid electrolyte.

[0002]

2. Description of the Related Art A phosphoric acid fuel cell power generator having a phosphoric acid electrolyte using a gas obtained by steam reforming a hydrocarbon-based raw fuel such as LNG or LPG or an alcohol-based raw fuel such as methanol as a fuel gas is, for example, carbonized. There is known a system shown in FIG. 3 including a fuel reformer for reforming a hydrogen-based raw fuel and a phosphoric acid fuel cell. In FIG. 3, the fuel reformer comprises a desulfurizer 2, a reformer 3 having a burner 4, and a carbon monoxide shift converter 5. The phosphoric acid fuel cell 6 includes a phosphoric acid electrolyte layer, an anode 7 and a cathode 8 that sandwich the same, and a cooling plate 9 having a cooling passage through which a cooling medium that removes heat generated during power generation flows. To be done.

With such a structure, raw fuel such as LNG and LPG flows through the desulfurizer 2 to desulfurize the sulfur content contained in the raw fuel that poisons the reforming catalyst in the reformer 3. The desulfurized raw fuel flows into the reformer 3, and the burner 4 uses the off-gas discharged from the anode 7 of the phosphoric acid fuel cell 6 as fuel.
The fuel gas is heated by the combustion gas burned at 1, and steam reformed into a gas containing hydrogen and carbon monoxide under the reforming catalyst. The steam-reformed gas is passed through the carbon monoxide shift converter 5 to convert carbon monoxide into carbon dioxide to form a hydrogen-rich reformed gas having a low carbon monoxide concentration. It is supplied to the anode 7 of the fuel cell 6.

The phosphoric acid fuel cell 6 generates a power by causing a cell reaction by the supplied reformed gas and the air supplied to the cathode 8.

[0005]

In the above fuel cell power generator, carbon monoxide contained in the gas reformed by the steam reformer 3 has a high energy level. However, since carbon monoxide poisons the electrode catalyst of the fuel cell and is harmful to the human body if it is released into the atmosphere, carbon monoxide is converted into carbon dioxide by the carbon monoxide transformer 5. There is a problem that the high energy of carbon oxide is not effectively used.

An object of the present invention is to provide a hybrid fuel cell, which is capable of effectively utilizing carbon monoxide having a high energy contained in the steam reformed gas delivered from the reformer, in a phosphoric acid fuel cell. A fuel cell power generator is provided.

[0007]

In order to solve the above problems, according to the present invention, a reformer for steam reforming a raw fuel into a gas containing hydrogen and carbon monoxide, and a reformer from this reformer A phosphoric acid fuel cell having a phosphoric acid electrolyte, comprising a solid oxide fuel cell having a solid electrolyte in which reformed gas is supplied to the anode, and an anode supplied with exhaust gas discharged from the anode of the fuel cell. The hybrid fuel cell power generator is provided.

Further, in the above hybrid fuel cell power generation device, a carbon monoxide transformer for transforming carbon monoxide contained in the exhaust gas discharged from the anode of the solid oxide fuel cell is provided in the preceding stage of the phosphoric acid fuel cell. Shall be provided.

[0009]

The gas containing hydrogen and carbon monoxide obtained by steam reforming the raw fuel in the reformer is supplied to the anode of the solid oxide fuel cell. Then, the solid oxide fuel cell causes a cell reaction by the gas supplied to the anode and the air supplied to the cathode separately to generate electricity. At this time, hydrogen and carbon monoxide react with the oxygen in the air as follows.

2H ₂ + O ₂ → 2H ₂ O ────────────── (1) 2CO + O ₂ → 2CO ₂ ─────────────── (2) Here, the exhaust gas discharged from the anode of the solid oxide fuel cell becomes a gas containing hydrogen that does not contribute to the cell reaction and carbon dioxide in which carbon monoxide is modified by the formula (2). The exhaust gas is supplied to the anode of the phosphoric acid fuel cell, and the air is separately supplied to the cathode, whereby the phosphoric acid fuel cell causes a cell reaction to generate electricity. The reaction between hydrogen and oxygen in the air at this time is according to the equation (1).

By the way, the steam-reformed gas containing hydrogen and carbon monoxide from the reformer is subjected to the reactions as in formulas (1) and (2) in the solid oxide fuel cell to generate electricity. At this time, since the electric power obtained by converting carbon monoxide into carbon dioxide can also be taken out, the electric conversion efficiency of the fuel cell power generator is improved. At this time, 2CO of the formula (2)
Increasing the utilization rate of carbon monoxide that generates electricity also by the reaction of + O ₂ → 2CO ₂ can reduce the concentration of carbon monoxide that poisons the electrode catalyst of the phosphoric acid fuel cell. This eliminates the need to install a carbon monoxide transformer.

Even when the utilization rate of carbon monoxide in the solid oxide fuel cell is low, the amount of carbon monoxide contained in the solid oxide fuel cell is smaller than in the conventional case. Therefore, the carbon monoxide transformer should be downsized. You can

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a system diagram of a hybrid fuel cell power generator having a phosphoric acid fuel cell and a solid oxide fuel cell according to an embodiment of the present invention. In FIG. 1, the same parts as those in the conventional example of FIG. 3 are designated by the same reference numerals, and the description thereof will be omitted. 1 is different from the conventional example as follows.

The carbon monoxide shift converter 5 shown in FIG. 3 is removed, and the solid oxide fuel cell 11 is installed at the subsequent stage of the reformer 3. The solid oxide fuel cell 11 includes a solid electrolyte (not shown), and an anode 12 and a cathode 13 that sandwich the solid electrolyte. Further, a cooler 15 for cooling the exhaust gas discharged from the anode 12 of the solid oxide fuel cell 11 is installed between the solid oxide fuel cell 11 and the phosphoric acid fuel cell 6.

With such a configuration, the steam-reformed gas containing hydrogen and carbon monoxide from the reformer 3 is supplied to the anode 12 of the solid oxide fuel cell 11 and separately supplied to the cathode 13. Generates power by causing a battery reaction. At this time, the heat generated during power generation is removed by the supplied air, and is maintained at a high operating temperature. The exhaust gas discharged from the anode 12 during power generation of the solid oxide fuel cell 11 is a gas containing hydrogen, carbon dioxide, and the like that do not contribute to the cell reaction. At this time, since the concentration of carbon monoxide can be lowered by increasing the utilization rate of carbon monoxide, the conventional carbon monoxide transformer for converting carbon monoxide is unnecessary.

Since this exhaust gas is at a high temperature close to the operating temperature, it is cooled to the operating temperature of the phosphoric acid fuel cell 6 by the cooler 15 and supplied to the anode 7 of the phosphoric acid fuel cell 6 and separately to the cathode 8. The supplied air causes a battery reaction to generate power. The heat generated during power generation is the cooling plate 9
The operating temperature is maintained by removing the heat from the cooling medium flowing through the cooling passage.

FIG. 2 is a system diagram of a hybrid fuel cell power generator having a phosphoric acid fuel cell and a solid oxide fuel cell according to another embodiment of the present invention. 2 is the same as FIG. 1 except that a carbon monoxide shifter 18 is installed between the cooler 15 and the phosphoric acid fuel cell 6. With such a configuration, during the cell reaction in the solid oxide fuel cell 11, when the utilization rate of carbon monoxide is low, a gas having a concentration according to the utilization rate of carbon monoxide that does not convert to carbon dioxide is emitted from the anode 12. Since the exhaust gas is discharged, after the exhaust gas is cooled by the cooler 15, the carbon monoxide shifter 18 shifts the carbon monoxide into carbon dioxide to reduce the carbon monoxide concentration,
By supplying a gas containing hydrogen to the anode 7 of the phosphoric acid fuel cell 6, it is possible to generate power as described above.

In the above case, the concentration of carbon monoxide contained in the gas discharged from the anode 12 of the solid oxide fuel cell 11 is lower than in the conventional case, so that the carbon monoxide transformer 18 can be miniaturized. it can. In this example, the reformed gas obtained by steam reforming a hydrocarbon-based raw fuel was described. However, a gas containing hydrogen and carbon monoxide obtained by steam reforming an alcohol-based raw fuel such as methanol in a reformer was used. The same effect can be obtained when used.

[0019]

As is apparent from the above description, according to the present invention, the solid electrolyte fuel cell according to the above-mentioned structure is provided with the gas containing hydrogen and carbon monoxide obtained by steam reforming the raw fuel in the reformer. When carbon dioxide is supplied to the battery to cause a battery reaction, carbon monoxide generates electricity by the reaction of becoming carbon dioxide, so that the high energy of carbon monoxide can be effectively used and the electric conversion efficiency can be increased.

Further, since carbon monoxide is converted to carbon dioxide in the solid oxide fuel cell, the phosphoric acid fuel cell is supplied with the fuel gas having a low carbon monoxide concentration, and thus the carbon monoxide transformer is unnecessary. Has the effect of becoming. When the utilization rate of carbon monoxide that converts carbon monoxide into carbon dioxide is low in a solid oxide fuel cell, the size can be reduced even if a carbon monoxide transformer is provided.

[Brief description of drawings]

FIG. 1 is a system diagram of a hybrid fuel cell power generator in which a phosphoric acid fuel cell and a solid oxide fuel cell according to an embodiment of the present invention are provided side by side.

FIG. 2 is a system diagram of a hybrid fuel cell power generator including a phosphoric acid fuel cell and a solid oxide fuel cell according to another embodiment of the present invention.

FIG. 3 is a system diagram of a conventional phosphoric acid fuel cell power generator.

[Explanation of symbols]

 2 Desulfurizer 3 Reformer 6 Phosphoric acid fuel cell 7 Anode 8 Cathode 11 Solid electrolyte fuel cell 12 Anode 13 Cathode 18 Carbon monoxide converter

Claims (2)

[Claims] 1. A solid electrolyte fuel comprising a reformer for steam reforming a raw fuel into a gas containing hydrogen and carbon monoxide, and a solid electrolyte in which the reformed gas from the reformer is supplied to an anode. A hybrid fuel cell power generator comprising a cell and an anode to which exhaust gas discharged from the anode of the fuel cell is supplied, and a phosphoric acid fuel cell having a phosphoric acid electrolyte. 2. The carbon monoxide shifter for transforming carbon monoxide contained in exhaust gas discharged from the anode of a solid oxide fuel cell according to claim 1, wherein the phosphoric acid fuel cell is provided in front of the phosphoric acid fuel cell. A hybrid fuel cell power generator characterized in that