JPH08298130A - Fuel cell power plant - Google Patents

Abstract

PURPOSE: To improve long period stability of cell performance by providing a specific constitution so as to prevent a blockade of a cathode gas flow path in the interior of a fuel cell, in a fuel cell power plant comprising an anode electrode and a cathode electrode. CONSTITUTION: In a fuel cell power plant comprising an anode electrode 6b and a cathode electrode 6c, in a inlet pipe of the cathode electrode 6c, filters 12a, 12b of removing impurities contained in fuel gas are set up in a route of the downstream in a confluent point of a delivery pipe of a cathode recycle blower 9 of circulating outlet gas of the cathode electrode 6c. In the filters 12a, 12b, preferably a permanent magnet is used to remove iron rust contained in fuel gas. In the filters 12a, 12b, preferably a contact cooler coming into direct contact with water is used to remove iron rust and salts in fuel gas.

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 plant, and more particularly to a fuel cell power plant for removing impurities in gas to improve long-term reliability of a fuel cell body.

[0002]

2. Description of the Related Art In a fuel cell power plant, hydrogen supplied to an anode (fuel electrode) and a cathode (air electrode)
Electric energy is taken out by a chemical reaction with oxygen supplied to the.

FIG. 3 is a block diagram of a conventional pressurized fuel cell power plant. Since a sulfur compound is added as an odorant to natural gas, which is one of the fuel gases, the sulfur compound is removed by the desulfurizer 1 and then sent to the reformer 2. The natural gas sent to the reformer 2 reacts with the steam from the steam separator 3 in the presence of the reforming catalyst to become a hydrogen-rich gas. The hydrogen-rich gas containing carbon monoxide that has exited the reformer 2 is reduced in carbon monoxide by the carbon monoxide shift converter 4,
Further, excess water is removed by the contact cooler 5 and sent to the anode 6a of the battery body 6.

On the other hand, air is generally used as the cathode gas, and the air pressurized by the air compressor 7 is directly sent to the cathode electrode 6c of the battery body 6 to obtain electric energy by the electrochemical reaction of hydrogen and oxygen. . Water and heat are generated as reaction products, and this heat is removed by flowing cooling water through the cooling plate 6a.

Further, the outlet of the anode 6b and the cathode 6
Part of the exhaust fuel and exhaust air at the c outlet is recirculated by the anode recycle blower 8 and the cathode recycle blower 9 in order to control the fuel utilization rate and oxygen utilization rate inside the cell. The remaining exhaust gas is sent to the reformer burner 2a and becomes a heat source for promoting the reforming reaction. Further, the fuel exhaust gas from the reformer 2 is sent to the auxiliary burner 10, is introduced together with the fuel exhaust gas of the auxiliary burner 10 into the gas turbine 11 which drives the air compressor 7, and after working there, becomes the plant exhaust gas.

[0006]

As described above, in the conventional fuel cell power plant, the air used as the cathode gas is directly supplied from the air compressor 7 to the cathode electrode 6c of the cell body 6. When air is used as the cathode gas, the oxygen content in the air is 21%, and it is necessary to supply about 5 times as much air to obtain the oxygen amount necessary for the actual reaction. Further, in order to increase the plant efficiency, it is necessary to reduce the pressure loss from the air compressor to the cathode electrode and reduce the power of the gas turbine.

Therefore, a large-diameter pipe is used as the air pipe as compared with the fuel pipe, and a carbon steel pipe is used instead of a stainless steel pipe having excellent corrosion resistance for cost reduction. However, carbon steel pipes rust due to oxygen and moisture in the air. In particular, in a system having a recycle blower that circulates the cathode outlet gas, rust is remarkably generated because the gas containing the battery-generated water is circulated. As a result, rust-containing air is supplied to the cathode electrode of the battery body, and it binds to the viscous phosphoric acid used as the electrolyte solution to block the cathode gas flow path inside the battery. Therefore, it is a cause of the battery voltage drop.

The present invention has been made to solve the above problems, and its object is to make the cathode gas system of a fuel cell power plant equipped with a filter or the like for removing impurities contained in the fuel gas, so that it is compact and inexpensive. Fuel cell power plant.

[0009]

In order to achieve the above object, claim 1 of the present invention provides a filter for removing impurities contained in a fuel gas in a fuel cell power plant comprising an anode and a cathode. It is characterized in that it is installed on the downstream side of the confluence point with the cathode recycle blower discharge pipe for circulating the cathode electrode outlet gas.

According to a second aspect of the present invention, in the fuel cell power plant according to the first aspect, a permanent magnet is used for the filter to remove iron rust contained in the fuel gas.

According to a third aspect of the present invention, in the fuel cell power plant according to the first aspect, iron rust and salts contained in the fuel gas are removed by using a contact cooler that is in direct contact with water on the filter. It is characterized by

[0012]

According to the first to third aspects of the present invention, impurities contained in the cathode gas, such as iron rust and salts, are removed by the filter installed at the cathode inlet of the battery main body to remove the cathode gas inside the battery. Prevents blockage of the flow path,
The long-term stability of battery performance can be improved.

[0013]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a system configuration diagram of an embodiment (corresponding to claim 1 and claim 2) of the present invention. The difference from the conventional fuel cell power generation plant of FIG. Filter 1 for removing impurities in gas from piping
2a, 12b and differential pressure gauges 13a, 13b for measuring the differential pressure between the inlet and the outlet of the filters 12a, 12b are installed in the downstream path of the confluence of the discharge pipes of the cathode recycle blower 9, and other points. Are the same, the same parts are designated by the same reference numerals, and duplicate description will be omitted.

In the figure, impurities contained in the air directly supplied from the air compressor 7 and the cathode outlet air supplied by the cathode recycle blower 9 are removed by the filter 12a or 12b. When the differential pressure gauge 13a attached to the filter 12a rises due to clogging during plant operation, the filter 12b is switched to and the element of the filter 12a is cleaned or replaced.

The rust generated on the surface of the carbon pipe in the air is
Magnetic iron oxide such as Fe (OH) ₂ and FeOOH. In a system with severe pressure loss in piping, iron rust can be effectively removed by using a permanent magnet as a filter.

FIG. 2 is a system configuration diagram of another embodiment (corresponding to claim 3) of the present invention. The difference from the embodiment of FIG. 1 is that the cathode electrode inlet pipe is used instead of the filter 12a or 12b. Since the contact cooler 14 for directly contacting the fuel gas and the water is installed and the other points are the same, the same parts are denoted by the same reference numerals and the duplicate description will be omitted.

In this embodiment, the contact cooler 14 can remove salts in the air as well as iron rust.
Therefore, particularly in a fuel cell plant installed near the coast, a large amount of salts is contained in the air, and the effect is remarkable.

As described above, according to this embodiment, impurities mainly composed of iron rust contained in the cathode gas can be removed while the plant is operating, and the impurities can be installed in the pipe without any special auxiliary equipment. You can In the system to which the cathode recycle is connected, it is effective to install a filter on the downstream side path of the branch point.

[0019]

As described above, the present invention (Claim 1)
According to claim 3), since the filter or the contact cooler is installed in the downstream side passage of the confluence of the cathode recycle blower, iron rust contained in the cathode gas and salts in the air during the plant operation are eliminated. Impurities which are the main components can be treated, and a compact and inexpensive fuel cell power plant cost can be provided.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of an embodiment of the present invention.

FIG. 2 is a system configuration diagram of another embodiment of the present invention.

FIG. 3 is a configuration diagram of a conventional fuel cell power plant system.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Desulfurizer, 2 ... Reformer, 2a ... Reformer burner, 3 ... Steam separator, 4 ... Carbon monoxide shift converter, 5 ... Contact cooler, 6 ... Battery body, 6a ... Cooling plate, 6b ... Anode very,
6c ... Cathode electrode, 7 ... Air compressor, 8 ... Anode recycling blower, 9 ... Cathode recycling blower,
10 ... Auxiliary burner, 11 ... Gas turbine, 12a, 12
b ... filter, 13a, 13b ... differential pressure gauge, 14 ... contact cooler.

Claims (3)

[Claims] 1. A fuel cell power plant comprising an anode and a cathode, wherein a filter for removing impurities contained in a fuel gas is provided downstream of a confluence point with a cathode recycle blower discharge pipe for circulating the cathode outlet gas. A fuel cell power plant that is installed on the side. 2. The fuel cell power plant according to claim 1, wherein a permanent magnet is used for the filter to remove iron rust contained in the fuel gas. 3. The fuel cell power plant according to claim 1, wherein iron rust and salts contained in the fuel gas are removed by using a contact cooler in direct contact with water on the filter.