CARBON MONOXIDE CLEAN-UP IN A PEM FUEL CELL SYSTEM
A fuel processor system contains an autothermal reactor (ATR) that produces a hydrogen-rich first gas stream containing carbon monoxide. Downstream of the ATR, a pressure swing adsorber produces a second hydrogen-rich gas stream containing 5 ppm carbon monoxide or more. Downstream of the PSA, there is a methanation reactor sized to reduce the CO level of the second stream below 5 ppm. A method of operating of proton exchange membrane fuel cell stack involves cooling the methanator output and feeding it into the stack as an anode fuel.
1 - 18 . (canceled)
19 . A method for reducing the carbon monoxide concentration of a hydrogen-containing gas stream comprising:
generating a first hydrogen-rich gas stream containing a first carbon monoxide level;
generating a second hydrogen-rich gas stream by passing the first stream through an adsorbent apparatus comprising a material that adsorbs carbon monoxide, wherein the second stream has a lower carbon monoxide level than the first stream; and
passing the second stream through a methanation reactor to produce a third stream with lower carbon monoxide content than the second stream.
20 . A method according to claim 19 , wherein the carbon monoxide content of the third stream is less than 5 ppm.
21 . A method according to claim 19 , wherein the carbon monoxide content of the third stream is less than 1 ppm.
22 . A method according to claim 19 , wherein the carbon monoxide content of the third stream meets requirements of a fuel cell stack.
23 . A method according to claim 19 , wherein the carbon monoxide content of the first stream is greater than 400 ppm and the carbon monoxide content of the second stream is less than 400 ppm.
24 . A method according to claim 23 , wherein the carbon monoxide content of the second stream is less than 100 ppm.
25 . A method according to claim 19 , wherein generating the first stream is accomplished in an autothermal reactor.
26 . A method according to claim 19 , wherein the adsorbent apparatus comprises a pressure swing adsorber.
27 . A method according to claim 26 , wherein the pressure swing adsorber comprises multiple fixed adsorbent-containing beds.
28 . A method according to claim 19 , wherein the adsorbent apparatus removes carbon dioxide form the first gas stream
29 . A method of operating a fuel cell, the fuel cell comprising an anode, a cathode, and a proton exchange membrane, the method comprising supplying the anode with a hydrogen-containing gas stream generated according to the method of claim 19 .
30 . A method according to claim 29 , wherein the hydrogen-containing gas stream has less than 5 ppm carbon monoxide.
31 . A method according to claim 29 , wherein the hydrogen-containing gas stream has less than 1 ppm carbon monoxide.
32 . A method of operating a fuel cell stack comprising an anode, cathode and a proton exchange membrane, the method comprising:
reacting a hydrocarbon fuel in an autothermal reactor to produce a hydrogen-rich first stream containing carbon monoxide;
passing the first stream through a pressure swing adsorber to produce a second stream lower in carbon monoxide than the first stream;
passing the second stream through a methanation reactor to produce a third stream lower in carbon monoxide than the second stream; and
supplying the anode of the fuel cell stack with the hydrogen-containing third stream.
33 . A method according to claim 32 , wherein the hydrogen-containing third stream has 5 ppm carbon monoxide or less.
34 . A method according to claim 32 , wherein the hydrogen-containing third stream has a carbon monoxide level of 1 ppm or less.
35 . A method according to claim 32 , wherein the second stream is free of carbon dioxide.