초록 ▼

A fuel cell system that routes anode effluent from one fuel cell stack to the anode side of another fuel cell stack to consume unused hydrogen in the production of electricity is disclosed. The routing of the anode effluent from one fuel cell stack to another is accomplished by providing flow paths

A fuel cell system that routes anode effluent from one fuel cell stack to the anode side of another fuel cell stack to consume unused hydrogen in the production of electricity is disclosed. The routing of the anode effluent from one fuel cell stack to another is accomplished by providing flow paths that connect the anode sides of the various fuel cell stacks together. The flow paths contain valves that are operable to selectively block flow through the various flow paths as desired. Optionally, the flow paths can be operated free of any valves. Methods of operating such fuel cell systems are also disclosed.

대표청구항 ▼

What is claimed is: 1. A method of operating a fuel cell system having a plurality of fuel cell stacks each operable to convert a hydrogen-containing anode reactant on an anode side of the fuel cell stack and an oxidant-containing cathode reactant on a cathode side of the fuel cell stack into elect

What is claimed is: 1. A method of operating a fuel cell system having a plurality of fuel cell stacks each operable to convert a hydrogen-containing anode reactant on an anode side of the fuel cell stack and an oxidant-containing cathode reactant on a cathode side of the fuel cell stack into electricity, a hydrogen-containing anode effluent on the anode side and an oxidant-containing cathode effluent on the cathode side, wherein the anode side of each fuel cell stack is connected to the anode side of a different one of the fuel cell stacks with individual discrete flow paths, the method comprising: (a) supplying a hydrogen-containing anode reactant stream to an anode side of at least one fuel cell stack of the plurality of fuel cell stacks for reaction therein and production of a first anode effluent stream; (b) supplying said first anode effluent stream to the anode side of at least one of the other fuel cell stacks of the plurality of fuel cell stacks via at least one of the individual discrete flow paths for reaction therein and production of a second anode effluent stream; (c) switching which fuel cell stack(s) receives said anode reactant stream; and (d) selectively venting a portion of anode effluent from the fuel cell system, said vented portion including nitrogen. 2. The method of claim 1, wherein selectively venting a portion of anode effluent includes selectively venting said portion of anode effluent from a same number of fuel cell stacks as a number of fuel cell stacks receiving said anode reactant stream while said fuel cell stacks are receiving said anode reactant stream. 3. A method of operating a fuel cell system having a plurality of fuel cell stacks each operable to convert a hydrogen-containing anode reactant on an anode side of the fuel cell stack and an oxidant-containing cathode reactant on a cathode side of the fuel cell stack into electricity, a hydrogen-containing anode effluent on the anode side and an oxidant-containing cathode effluent on the cathode side, wherein the anode side of each fuel cell stack is connected to the anode side of a different fuel cell stack with a flow path, the method comprising: (a) supplying a hydrogen-containing anode reactant stream to an anode side of at least one fuel cell stack of the plurality of fuel cell stacks for reaction therein and production of a first anode effluent stream; (b) supplying said first anode effluent stream to the anode side of at least one of the other fuel cell stacks of the plurality of fuel cell stacks via the flow paths for reaction therein and production of a second anode effluent stream; (c) switching which fuel cell stack(s) receives said anode reactant stream; and (d) selectively venting a portion of anode effluent from a fuel cell stack other than said at least one fuel cell stack receiving said anode reactant stream while said at least one fuel cell stack is receiving said anode reactant stream, said vented portion including nitrogen. 4. The method of claim 1, further comprising blocking flow through at least one of the flow paths. 5. The method of claim 4, further comprising switching which at least one flow path is blocked when said fuel cell stack(s) that receives said anode reactant stream is switched. 6. The method of claim 1, further comprising comparing an operating condition of the fuel cell system with empirical data and wherein switching which fuel cell stack(s) that receive said anode reactant stream is based on said comparison. 7. The method of claim 1, wherein switching which fuel cell stack(s) that receive said anode reactant stream is based on an algorithm. 8. A method of operating a fuel cell system having a plurality of fuel cell stacks each operable to convert a hydrogen-containing anode reactant on an anode side of the fuel cell stack and an oxidant-containing cathode reactant on a cathode side of the fuel cell stack into electricity, a hydrogen-containing anode effluent on the anode side and an oxidant-containing cathode effluent on the cathode side, wherein the anode side of each fuel cell stack is connected to the anode side of a different fuel cell stack with a flow path, the method comprising: (a) supplying a hydrogen-containing anode reactant stream to an anode side of at least one fuel cell stack of the plurality of fuel cell stacks for reaction therein and production of a first anode effluent stream; (b) supplying said first anode effluent stream to the anode side of at least one of the other fuel cell stacks of the plurality of fuel cell stacks via the flow paths for reaction therein and production of a second anode effluent stream; and (c) switching which fuel cell stack(s) receives said anode reactant stream at a frequency of at least an order of magnitude faster than a nitrogen buildup time in the fuel cell system. 9. The method of claim 1, further comprising continuously venting said portion of anode effluent produced by the fuel cell system. 10. The method of claim 1, wherein supplying an anode reactant stream to an anode side of at least one fuel cell stack includes supplying an anode reactant stream to the anode sides of only one half of the plurality of fuel cell stacks and switching which fuel cell stack(s) receives said anode reactant stream includes switching to supplying said anode reactant stream to the anode sides of only the other half of the plurality of fuel cell stacks and further comprising varying which fuel cell stacks are included in each half. 11. The method of claim 1, further comprising limiting a direction of flow through the flow paths to a single direction with a directional flow limiting device in the flow paths. 12. A method of operating a fuel cell system having a plurality of fuel cell stacks each operable to convert a hydrogen-containing anode reactant on an anode side of the fuel cell stack and an oxidant-containing cathode reactant on a cathode side of the fuel cell stack into electricity, a hydrogen-containing anode effluent on the anode side and an oxidant-containing cathode effluent on the cathode side, wherein the anode side of each fuel cell stack is connected to the anode side of a different fuel cell stack with a flow path, the method comprising: (a) supplying a hydrogen-containing anode reactant stream to an anode side of at least one fuel cell stack of the plurality of fuel cell stacks for reaction therein and production of a first anode effluent stream; (b) supplying said first anode effluent stream to the anode side of at least one of the other fuel cell stacks of the plurality of fuel cell stacks via the flow paths for reaction therein and production of a second anode effluent stream; (c) switching which fuel cell stack(s) receives said anode reactant stream; and (d) selectively venting a portion of anode effluent from the fuel cell system, said vented portion including nitrogen, wherein the plurality of fuel cell stacks is at least three fuel cell stacks and said first anode effluent stream is supplied in series to the anode sides of all of the other fuel cell stacks of the plurality of fuel cell stacks via the flow paths for reaction therein and production of said second anode effluent stream. 13. The method of claim 1, further comprising switching which fuel cell stack(s) of the other fuel cell stacks that receive said first anode effluent stream. 14. A method of operating a fuel cell system having at least three fuel cell stacks each operable to convert a hydrogen-containing anode reactant on an anode side of the fuel cell stack and an oxidant-containing cathode reactant on a cathode side of the fuel cell stack into electricity, a hydrogen-containing anode effluent on the anode side and an oxidant-containing cathode effluent on the cathode side, the method comprising: (a) supplying a hydrogen-containing anode reactant stream to the anode sides of each fuel cell stack in a first segment of the system for reaction therein to produce at least one first segment anode effluent stream, wherein said first segment comprises one or more fuel cell stacks of the at least three fuel cell stacks; (b) supplying said at least one first segment anode effluent stream to the anode sides of fuel cell stacks in a second segment of the system for reaction therein to produce at least one second segment anode effluent stream, wherein said second segment comprises the remaining fuel cell stacks of the at least three fuel cell stacks; and (c) changing a selection of said one or more fuel cell stacks that comprise said first segment. 15. The method of claim 14, further comprising selectively venting a portion of anode effluent from the fuel cell system, said vented portion including nitrogen. 16. The method of claim 15, wherein selectively venting a portion of anode effluent includes selectively venting said portion of anode effluent from a same number of second segment fuel cell stacks as a number of fuel cell stacks that comprise said first segment. 17. The method of claim 16, wherein selectively venting a portion of anode effluent includes selectively venting a portion of said second segment anode effluent. 18. The method of claim 14, wherein said first segment contains a plurality of fuel cell stacks that produce a plurality of first segment anode effluent streams and further comprising supplying each first segment anode effluent stream to a different fuel cell stack of said second segment such that each first segment fuel cell stack is operating in series with a different second segment fuel cell stack. 19. The method of claim 14, further comprising comparing an operating condition of the fuel cell system with empirical data and wherein changing a selection of said one or more fuel cell stacks that comprise said first segment is based on said comparison. 20. The method of claim 14, wherein changing a selection of said one or more fuel cell stacks that comprise said first segment is based on an algorithm. 21. The method of claim 14, wherein changing a selection of said one or more fuel cell stacks that comprise said first segment is done at a frequency of at least an order of magnitude faster than a nitrogen buildup time in the fuel cell system. 22. The method of claim 14, further comprising continuously venting a portion of anode effluent produced by the fuel cell system. 23. The method of claim 1, wherein said switching includes changing which fuel cell stacks are operating in series with one another. 24. The method of claim 23, wherein said switching includes changing which fuel cell stacks are operating in parallel with one another. 25. The method of claim 14, wherein a first group of at least one fuel cell stack in each of said first and second segments operating in series operates in parallel with a second group of a different at least one fuel cell stack in each of said first and second segments operating in series. 26. The method of claim 25, further comprising changing which fuel cell stacks are in said first and second groups. 27. The method of claim 14, wherein (a) includes supplying said hydrogen-containing anode reactant in a quantity sufficient to provide a stoichiometric quantity of hydrogen of at least 1.0 to at least one of said second segment fuel cell stacks.