Integrated fuel cell system
View Patent ↗A simplified PEM fuel cell system is integrated with a fuel processor and an exhaust gas oxidizer to ensure clean emissions. The fuel cell has an operating temperature of 100–200° C., and utilizes reformate fuel having a carbon monoxide level greater than 1000 parts per million.
1. A method of operating a fuel cell system, comprising:
converting a flow of hydrocarbon into a fuel stream comprising hydrogen and carbon monoxide;
reacting a portion of the carbon monoxide with steam to produce additional hydrogen in the fuel stream;
flowing the fuel stream through a polymer membrane fuel cell having a temperature greater than 120° C.;
exhausting the fuel stream from the fuel cell, wherein the exhausted fuel stream comprises at least 1,000 parts per million carbon monoxide; and
flowing the exhausted fuel stream to an oxidizer wherein the carbon monoxide in the exhausted fuel stream is reduced to a level less than 100 parts per million.
2. The method of claim 1 , wherein the act of converting the flow of hydrocarbon comprises communicating the flow of hydrocarbon through an autothermal reactor.
3. The method of claim 2 , further comprising:
flowing natural gas through the reactor at a first molar flow rate;
flowing oxygen through the reactor at a second molar flow rate having a ratio in the range of 0.5–0.6 with respect to the first molar flow rate; and
flowing steam through the reactor at a third molar flow rate having a ratio in the range of 2.5–4.0 with respect to the first molar flow rate.
4. The method of claim 3 , wherein the natural gas comprises methane.
5. The method of claim 1 , further comprising:
operating the fuel cell at a temperature in the range 150–200° C.
6. The method of claim 1 , wherein the fuel cell comprises a polybenzimidazole polymer exchange membrane.
7. The method of claim 1 , wherein the exhausted fuel stream comprises at least 3,000 parts per million carbon monoxide.
8. The method of claim 1 , wherein the act of converting the hydrocarbon comprises flowing the hydrocarbon through a conversion reactor.