Fuel cell power system

Abstract

The present invention provides a fuel cell power system and a power generating method in which the rise of concentration of water vapor and carbon dioxide in the direction of the anode gas flow is controlled to enhance the electromotive force in the downstream region of the anode gas flow, thereby improving the power generating efficiency. A mixed gas of a hydrocarbon and water vapor and/or carbon dioxide or a reformed version of said mixed gas having an oxygen atom/carbon atom ratio (O/C ratio) of 2 or higher is supplied from a spot upstream in the direction of the anode gas flow while a hydrocarbon or a mixed gas of a hydrocarbon and water vapor and/or carbon dioxide having an O/C ratio of lower than 2 is supplied supplementally from a spot downstream, and the gas supplied supplementally from the downstream side is reformed by making use of water vapor and carbon dioxide generated by the electrochemical reactions upstream of the anode gas flow and is utilized for power generation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a lateral sectional view showing the makeup of the fuel cell power system in an embodiment of the present invention.

FIG. 2 is a graphic illustration of the water vapor and/or carbon dioxide flow rate in the direction of the anode gas flow in the instant embodiment of the present invention.

FIG. 3 is a graphic illustration of the water vapor and/or carbon dioxide flow rate in the direction of the anode gas flow in the prior art.

FIG. 4 is a graph showing the electromotive force in the direction of the anode gas flow.

FIG. 5 is a lateral sectional view illustrating another embodiment of the present invention.

FIG. 6 is a plan sectional view of still another embodiment of the present invention.

FIG. 7 is a lateral sectional view taken along the line A-A of FIG. 6.

Claims

1. A fuel cell power system comprising: fuel cells each having an anode positioned on one side and a cathode on the other side, with an electrolyte being interposed between the anode and the cathode,in which a hydrocarbon or a reformed hydrocarbon gas is used as a fuel,two types of anode gases differing in the oxygen atom/carbon atom ratio (O/C ratio) from each other are supplied to said anode,a gas with a higher O/C ratio is supplied from an upstream side in the direction of the anode gas flow anda gas with a lower O/C ratio is supplied from a downstream side.

2. The fuel cell power system according to claim 1 wherein the anode gas with a lower O/C ratio is supplied from a plural spots along the direction of the anode gas flow.

3. The fuel cell power system according to claim 1 wherein the O/C ratio in the anode gas supplied from the upstream side is 2 or higher.

4. The fuel cell power system according to claim 1 wherein the O/C ratio in the anode gas supplied from the downstream side is lower than 2.

5. The fuel cell power system according to claim 1 wherein the O/C ratio in the anode gas supplied from the upstream side is 2 or higher and the O/C ratio in the anode gas supplied from the downstream side is lower than 2.

6. The fuel cell power system according to claim 1 wherein the anode gas with a higher O/C ratio comprises a mixture of a hydrocarbon with water vapor and/or carbon dioxide.

7. The fuel cell power system according to claim 1 wherein the anode gas with a lower O/C ratio comprises a hydrocarbon or a mixture of a hydrocarbon with water vapor and/or carbon dioxide.

8. A fuel cell power generating method comprising the steps of: supplying an anode gas containing a hydrocarbon or a reformed hydrocarbon gas and a cathode gas composed of air to each fuel cell having an anode and a cathode with an electrolyte disposed between the anode and the cathode;supplying a gas with a higher oxygen atom/carbon atom ratio (O/C ratio) from an upstream side in the direction of the anode gas flow;supplying a gas with a lower O/C ratio from a downstream side in the direction of the anode gas flow;reforming the gas with a lower O/C ratio supplied from the downstream side, by making use of water vapor and carbon dioxide generated by an electrochemical reaction in a region upstream in the direction of the anode gas flow, to utilize as a power generating fuel.

9. The fuel cell power generating method according to claim 8 wherein the gas with an O/C ratio of 2 or higher is flown from the upstream side in the direction of the anode gas flow, and the gas with an O/C ratio of lower than 2 is flown from the downstream side in the direction of the anode gas flow.

10. The fuel cell power generating method according to claim 9 wherein the anode gas with an O/C ratio of lower than 2 is supplied from plural spots in the direction of the anode gas flow.

11. The fuel cell power generating method according to claim 10 wherein the amount supplied of the gas with an O/C ratio of lower than 2 is controlled so that the O/C ratio in the anode gas is maintained at 2 or higher in each region in the direction of the anode gas flow.

12. A fuel cell power system comprising: fuel cells each having an anode and a cathode with an electrolyte interposed between the anode and the cathode,which is designed to generate electric power by supplying an anode gas containing a hydrocarbon or a reformed hydrocarbon gas and a cathode gas composed of air,in which there are provided anode gas supply channels designed to supply the anode gas from at least two spots on an upstream side and a downstream side in the direction of said anode gas flow,an anode gas with a higher O/C ratio is supplied from the upstream side and an anode gas with a lower O/C ratio is supplied from the downstream side, andthere is provided a means for preventing a rise of a gas temperature in a gas supply channel through which the anode gas with a lower O/C ratio is supplied.

13. The fuel cell power system according to claim 12 wherein the O/C ratio in the anode gas with a higher O/C ratio is 2 or higher, and the O/C ratio in the anode gas with a lower O/C ratio is lower than 2.

14. The fuel cell power system according to claim 13 wherein a gas, to which atomized water has been sprayed with the O/C ratio kept below 2, is used as the anode gas with an O/C ratio of lower than 2.