JPH1167251A - Fuel cell power generating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell power generating device capable of making a purge gas line compact and reducing a cost by using air as a purge gas of a housing container. SOLUTION: This fuel cell power generating system has a fuel cell 20 comprising an anode and a cathode and generating power with a cathode gas containing oxygen and an anode gas containing hydrogen, a housing container 21 for housing the fuel cell 20, a reformer 22 for burning an anode exhaust gas exhausted from the anode and a cathode exhaust gas exhausted from the cathode, reforming a fuel gas containing water vapor by the burning heat, and supplying the reformed gas as an anode gas to the anode, a carbon dioxide gas recycling line 7 for supplying the burned exhaust gas from the reformer 22 to the cathode, an air line 8 for supplying air to the carbon dioxide recycling line 7, and a turbine compressor 28 for driving a turbine with the cathode exhaust gas to compress air and supplying the compressed air to the air line 8. A purge gas line 14 branched from the air line 8 and for supplying a purge gas to the housing container 21 is arranged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fuel cell power generator for supplying air as a purge gas for a fuel cell storage container.

[0002]

2. Description of the Related Art Molten carbonate fuel cells have features not found in conventional power generators, such as high efficiency and low environmental impact, and have attracted attention as power generation systems following hydro, thermal and nuclear power. Currently, intensive research is underway.

FIG. 2 is a diagram showing an example of a power generation facility using a molten carbonate fuel cell using city gas as fuel. In the figure, a power generation facility is a reformer 22 for reforming a fuel gas (city gas) mixed with steam into an anode gas containing hydrogen.
And a fuel cell 20 that generates power from a cathode gas containing oxygen and an anode gas containing hydrogen.
The anode gas produced in Step 2 is supplied to the fuel cell 20 through the anode gas line 2, and most of the anode gas is consumed in the fuel cell 20 to become the anode exhaust gas. Supplied. The fuel cell 20 is stored in a storage container 21.

[0004] The catalytic combustor 23 burns combustible components (hydrogen, carbon monoxide, methane, etc.) in the anode exhaust gas to generate a high-temperature combustion exhaust gas, which is supplied to a heating chamber of the reformer 22 and used by the combustion exhaust gas. The reforming chamber is heated, and the fuel gas is reformed by the reforming catalyst in the reforming chamber to produce anode gas. The anode gas exchanges heat with the fuel gas mixed with the steam flowing through the fuel gas line 1 by the fuel preheater 24, and after being cooled, is supplied to the anode of the fuel cell 20. Further, the combustion exhaust gas exiting the heating chamber is supplied to the cathode by the carbon dioxide gas blower 32 in the carbon dioxide gas recycling line 7. The combustion exhaust gas contains a large amount of carbon dioxide, and serves as a supply source of carbon dioxide required for the battery reaction. Air from the air line 8 is supplied to the outlet side of the carbon dioxide gas blower 32 to supply oxygen required for a cathode cell reaction. Part of the cathode exhaust gas discharged from the cathode is supplied to the cathode by the circulation line 3. The cathode exhaust gas, the combustion exhaust gas, and the air are mixed to form a cathode gas, which is supplied to the cathode.

The cathode gas undergoes a cell reaction in the fuel cell 20 to become a high-temperature cathode exhaust gas. A part of the cathode gas is supplied to the catalytic combustor 23 through the cathode exhaust line 5, and the rest is compressed in the exhaust heat utilization line 6. After the power is recovered by the turbine compressor 28 that drives the compressor, the heat energy is further recovered by the exhaust heat recovery steam generator 30 and discharged outside the system. The steam generated by the exhaust heat recovery steam generator 30 enters the fuel gas line 1 via the steam line 9,
The mixture with the fuel gas is sent to the reformer 22.

A part of the combustion exhaust gas discharged from the reformer 22 is cooled by a cooler 36 in a purge gas line 10 and water is removed by a steam-water separator 37, and is then stored in a storage container 21 by a purge gas blower 38. Supplied. Since the combustion exhaust gas has a low oxygen content, it is used as suitable for a place where an anode gas containing hydrogen is used, such as the fuel cell 20. The purge gas in the storage container 21 is discharged through the purge gas discharge line 11.

[0007]

A part of the combustion exhaust gas (approximately 580 ° C.) discharged from the reformer 22 is cooled to approximately 50 ° C. in the purge gas line 10 and supplied to the storage container 21 as a purge gas. In the purge gas line 10, in order to perform such cooling, the cooler 36, the steam-water separator 3
7 is required, and a purge gas blower 38 for sending the cooled combustion exhaust gas into the storage container 21 is required, which has been an obstacle to downsizing and cost reduction of the fuel cell power generator.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a fuel cell power generator in which a purge gas line is made compact by using air as a purge gas for a containment vessel to reduce the size and cost of the purge gas line. I do.

[0009]

In order to achieve the above object, according to the first aspect of the present invention, there is provided a fuel cell comprising a cathode and an anode, and generating electricity from a cathode gas containing oxygen and an anode gas containing hydrogen. A storage container, a reformer that burns anode exhaust gas discharged from the anode and cathode exhaust gas discharged from the cathode, reforms a fuel gas containing water vapor with the heat, and supplies the reformed fuel gas to the anode as anode gas; A carbon dioxide gas recycling line for supplying combustion exhaust gas from the reformer to the cathode, an air line for supplying air to the carbon dioxide gas recycling line, and a turbine driven by the cathode exhaust gas to compress air and supply it to the air line A turbine compressor
And a purge gas line branched from the air line to supply a purge gas to the storage container.

[0010] The compressed air supplied to the cathode is generated by a turbine compressor using cathode exhaust gas. Generally, the amount of air supplied by a turbine compressor is larger than the amount of air required by a fuel cell plant, and may be partially released to the atmosphere. Especially when the load is low, the air becomes excessive. Since the supply of the barge gas to the storage container is often performed at a low load, the surplus air can be effectively used. The safety is ensured by installing a hydrogen detector in the containment vessel and monitoring the leakage of hydrogen. Further, since a cooler, a steam separator, a purge gas blower, and the like used in the conventional purge gas line are not required, a compact apparatus can be provided, operation can be facilitated, and plant cost can be reduced.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an overall configuration diagram of a fuel cell power generation device according to an embodiment of the present invention. In this figure, FIG.
Those having the same functions as those described above are denoted by the same reference numerals. The fuel cell power generator includes a reformer 22 that reforms a fuel gas containing steam into an anode gas containing hydrogen, and a fuel cell 2 that generates electricity from the anode gas and a cathode gas containing oxygen and carbon dioxide.
0. The fuel cell 20 is stored in a storage container 21. The anode exhaust gas discharged from the fuel cell 20 is supplied to the catalytic combustor 23 through the anode exhaust gas line 4 and burns using a combustion catalyst together with a part of the cathode exhaust gas containing oxygen. The reformer 22 comprises a reforming chamber and a catalytic combustor 23, which convert a city gas containing water vapor into a reformed gas by a catalyst.
And a heating chamber for heating the reforming chamber with the combustion exhaust gas from the furnace. Combustion exhaust gas containing carbon dioxide is supplied to the cathode by a carbon dioxide gas recycle line 7, air containing oxygen is supplied by an air line 8, and a part of the cathode exhaust gas is circulated by a circulation line 3, and these are mixed. And supplied as cathode gas. The amount of circulating gas in the circulation line 3 is adjusted by a flow control valve 40.

The city gas containing natural gas as a component is supplied by a fuel gas line 1 and, after sulfuric acid is removed by a desulfurizer 26, is mixed with steam from a steam line 9 to form a fuel preheater 2.
The preheater 4 enters the reforming chamber of the reformer 22. The anode gas generated from the reforming chamber is heated by the fuel preheater 24 through the anode gas line 2 and then heated by the fuel cell 20.
Is supplied to the anode. At the cathode of the fuel cell 20, the carbon dioxide gas from the carbon dioxide gas recycling line 7, the air from the air line 7, and the cathode exhaust gas from the circulation line 3 are mixed to form a cathode gas. Supplied by Fuel cell 2
Numeral 0 is supplied with the anode gas and the cathode gas to generate power. Anode exhaust gas containing steam and unburned components is discharged by the reaction at the anode, and supplied to the catalytic combustor 23 through the anode exhaust gas line 4. A part of the cathode exhaust gas generated by the reaction at the cathode is circulated to the cathode by the circulation line 3, another part is supplied to the catalytic combustor 23 by the cathode exhaust line 5, and the remaining part is to the exhaust heat utilization line 6. Supplied.

The catalytic combustor 23 is supplied with anode exhaust gas and cathode exhaust gas of the fuel cell 20. Since the fuel utilization of the fuel cell is about 80%, the anode exhaust gas contains 20%.
% Of fuel components. Cathode exhaust gas contains oxygen necessary for combustion. The combustion exhaust gas from the heating chamber of the reformer 22 contains carbon dioxide, which is necessary for the battery reaction at the cathode, and is supplied to the cathode by the carbon dioxide gas recycling line 7.

The carbon dioxide gas recycle line 7 is provided with a carbon dioxide gas blower 32, the circulation line 3 is connected to the inlet side of the carbon dioxide gas blower 32, and the air line 8 is connected to the outlet side. , 7, and 8 are sent to the cathode. A part of the cathode exhaust gas is supplied to the exhaust heat utilization line 6, and after driving the turbine compressor 28, is supplied to the exhaust heat recovery steam generator 30. In the heat recovery steam generator 30, the feed water is supplied to the turbine compressor 28.
The exhaust gas that drives the turbine is turned into steam and supplied to the fuel gas line 1 through the steam line 9. The exhaust gas from the exhaust heat recovery steam generator 30 is released to the atmosphere.

The air enters the compressor of the turbine compressor 28, is pressurized, and is supplied to the air line 8 via a check valve 45. The air is pressurized by the air blower 34 in the bypass line 12 and supplied to the air line 8. Air blower 34
A check valve 44 is provided on the inlet side, and a tie line 13 connecting the compressor outlet side is provided. Air blower 34
Is used as a backup for the turbine compressor 28. When the plant is started, the amount of cathode exhaust gas is small, so that the air blower 34 driven by an electric motor is used.

A purge gas line 14 is provided in the storage container 21 from the compressor outlet side of the turbine compressor 28 to supply air to the storage container 21. A check valve 46 and a flow control valve 41 are provided in the purge gas line 14 to prevent backflow and adjust the flow rate. Further, a check valve 4 is provided from the outlet side of the air blower 34.
An air auxiliary line 15 connected to the outlet of the check valve 46 of the purge line 14 through 7 is provided so that backup by the air blower 34 can be performed. Containment container 2
1 through the flow control valve 42 to supply the exhaust gas of the containment vessel 21 to the catalytic combustor 23 through the purge gas exhaust line 16
Is provided to supply oxygen to the catalytic combustor 23.

An anode gas containing hydrogen is supplied from the anode to the fuel cell 20 to perform a cell reaction. Since this gas may leak into the containment vessel 21, a certain ratio of oxygen contained in the air of the purge gas to oxygen is contained. To avoid mixing
A hydrogen detector (not shown) is provided to constantly monitor hydrogen leakage. Thereby, even if the purge gas of the storage container 21 is air, it can be operated safely.

[0018]

As is apparent from the above description, the present invention requires the use of air compressed by a turbine compressor driven by cathode exhaust gas as a purge gas for a containment vessel, thereby making it possible to use conventional combustion exhaust gas. This eliminates the need for equipment such as a cooler, a steam separator, and a purge gas blower, resulting in a compact device, improved operability and reduced plant cost. Further, since the excess air of the turbine compressor is effectively used, the plant efficiency is improved.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a fuel cell power generation device according to an embodiment of the present invention.

FIG. 2 is an overall configuration diagram of a conventional fuel cell power generator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel gas line 2 Anode gas line 3 Circulation line 4 Anode exhaust gas line 5 Cathode exhaust gas line 6 Exhaust heat utilization line 7 Carbon dioxide gas recycle line 8 Air line 9 Steam line 12 Bypass line 13 Tie line 14 Purge gas line 15 Air auxiliary line 16 Purge gas Discharge line 20 Fuel cell 21 Container 22 Reformer 23 Catalytic combustor 24 Fuel preheater 26 Desulfurizer 28 Turbine compressor 30 Exhaust heat recovery steam generator 32 Carbon dioxide gas blower 34 Air blower 40, 41, 42 Flow control valve 44, 45, 46, 47 check valve

Claims (1)

[Claims] 1. A fuel cell comprising a cathode and an anode and generating electricity from a cathode gas containing oxygen and an anode gas containing hydrogen, a storage container for storing the fuel cell, an anode exhaust gas discharged from the anode and an anode exhaust gas discharged from the cathode. A reformer that burns a cathode exhaust gas, reforms a fuel gas containing water vapor with the heat, and supplies the reformed fuel gas to the anode as an anode gas, a carbon dioxide gas recycling line that supplies the combustion exhaust gas from the reformer to the cathode, A fuel cell power generator comprising: an air line that supplies air to the carbon dioxide gas recycling line; and a turbine compressor that drives a turbine by the cathode exhaust gas to compress air and supply the compressed air to the air line. A purge gas line for branching and supplying a purge gas to the storage container is provided. Fuel cell power generator.