Staged lean combustion for rapid start of a fuel processor
View Patent ↗A fuel processor for rapidly achieving operating temperature during startup. The fuel processor includes a reformer, a shift reactor, and a preferential oxidation reactor is provided for deriving hydrogen for use in creating electricity in a plurality of fuel cells. A first combustion heater system is coupled to at least one of the reformer, the shift reactor, and the preferential oxidation reactor to preheat the component during a rapid startup sequence. That is, the first combustion heater system is operable to produce thermal energy as a product of the combustion of air and fuel in the form of a first heated exhaust stream. This first heated exhaust stream is then used to heat the component directly or by using a heat exchanger type system. The first heated exhaust stream is also used by a second combustion device as a source of oxygen or diluent.
1. A fuel processor for rapidly achieving operating temperature, said fuel processor comprising:
a reformer converting a hydrogen-containing fuel to H 2 -containing reformate;
a shift reactor in fluid communication with said reformer, said shift reactor being operable to reduce carbon monoxide levels of said reformate;
a preferential oxidation reactor in fluid communication with said shift reactor, said preferential oxidation reactor being operable to further reduce carbon monoxide levels of said reformate exiting said shift reactor; and
a first combustion heater system coupled to at least one of said reformers said shift reactor, and said preferential oxidation reactor, said first combustion heater system operated in a lean state to produce thermal energy as a product of internal combustion of air and fuel in the form of a first heated exhaust stream that is passed through said at least one of said reformer, said shift reactor, said preferential oxidation reactor; a second combustion heater system coupled to at least another of said reformer, said shift reactor, and said preferential oxidation reactor, said second combustion heater system operated to produce thermal energy as a product of the combustion of air and fuel in the form of a second heated exhaust stream that is passed through said at least another of said reformer, said shift reactor, and said preferential oxidation reactor.
2. The fuel processor according to claim 1 , wherein said second combustion heater further comprises an air inlet providing fresh air thereto.
3. The fuel processor according to claim 1 , wherein said second combustion heater system is positioned in series with said first combustion heater system.
4. The fuel processor according to claim 3 , wherein said second combustion heater further comprises a first inlet providing fresh air thereto and a second inlet in fluid communication with said first heated exhaust stream.
5. The fuel processor according to claim 4 , wherein said first heated exhaust stream is used to dilute said fresh air to control the temperature of said second heated exhaust stream.
6. The fuel processor according to claim 1 , further comprising:
a control valve system selectively diverting said first heated exhaust stream from said first combustion heater system from passing through said shift reactor.
7. The fuel processor according to claim 1 , further comprising:
a heat exchanger operatively associated with at least one of said reformer, said shift reactor, and said preferential oxidation reactor, said heat exchanger being exposed to at least one of said first heated exhaust stream and said second heated exhaust stream for heating said at least one of said reformer, said shift reactor, and said preferential oxidation reactor.
8. The fuel processor according to claim 1 , further comprising:
a spray vaporization zone coupled downstream from said second combustion heater system, said spray vaporization zone being operable to maintain a predetermined temperatures of said second heated exhaust stream.
9. The fuel processor according to claim 1 , further comprising:
a control valve system selectively routing an O 2 -containing cathode effluent from a fuel cell stack to a catalyst combustor and said second combustion heater system.
10. The fuel processor according to claim 9 , wherein said control valve system comprises:
a combustor air control valve selectively routing one of a group consisting of air and said O 2 -containing cathode effluent to said catalyst combustor; and
a cathode back pressure valve selectively applying a fluid back pressure to facilitate routing of said O 2 -containing cathode effluent to said catalyst combustor.
11. The fuel processor according to claim 1 , wherein said combustion of said air and said fuel in said first combustion heater system is lean of stoichiometric condition and said combustion of said air and said fuel in said second combustion heater system is generally near ideal stoichiometric condition.
12. The fuel processor according to claim 1 , further comprising:
a catalyst combustor positioned in series upstream from said second combustion heater system.
13. The fuel processor according to claim 1 , further comprising:
a catalyst combustor positioned in series downstream from said second combustion heater system.
14. The fuel processor according to claim 1 , further comprising:
a catalyst combustor positioned such that an output of said catalyst combustor is input downstream of said second combustion heater system.
15. A fuel processor comprising:
a reformer converting a hydrogen-containing fuel selected from the group consisting of alcohol and hydrocarbons to H 2 -containing reformate;
a shift reactor in fluid communication with said reformer, said shift reactor being operable to reduce carbon monoxide levels of said reformate;
a preferential oxidation reactor in fluid communication with said shift reactor, said preferential oxidation reactor being operable to further reduce carbon monoxide levels of said reformate exiting said shift reactor;
a first combustion heater system coupled to at least one of said reformer, said shift reactor, and said preferential oxidation reactor, said first combustion heater system operated in a lean state to produce thermal energy as a product of internal combustion in the form of a first heated exhaust stream that is passed through said at least one of said reformer, said shift reactor, and said preferential oxidation reactor; and
a second combustion heater system coupled to at least another of said reformer, said shift reactor, and said preferential oxidation reactor, said second combustion heater system operated in a slightly lean state to produce thermal energy as a product of combustion in the form of a second heated exhaust stream that is passed through said at least another of said reformer, said shift reactor, and said preferential oxidation reactor.
16. The fuel processor according to claim 15 , wherein said second combustion heater further comprises an air inlet providing fresh air thereto.
17. The fuel processor according to claim 15 , wherein said second combustion heater system is positioned in series with said first combustion heater system.
18. The fuel processor according to claim 17 , wherein said second combustion heater further comprises a first inlet providing fresh air thereto and a second inlet in fluid communication with said first heated exhaust stream.
19. The fuel processor according to claim 18 , wherein said first heated exhaust stream Is used to dilute said fresh air to control the temperature of said second heated exhaust stream.
20. The fuel processor according to claim 17 , further comprising:
a first control valve system selectively routing said first heated exhaust stream to said second combustion heater system during a startup cycle.
21. The fuel processor according to claim 15 , further comprising:
a spray vaporization zone coupled downstream from said second combustion heater system, said spray vaporization zone being operable to maintain a predetermined temperatures of said second heated exhaust stream.
22. The fuel processor according to claim 15 , further comprising:
a second control valve system selectively routing an O 2 -containing cathode effluent from a fuel cell stack to a catalyst combustor and said second combustion heater system.
23. The fuel processor according to claim 22 , wherein said second control valve system comprises:
a combustor air control valve selectively routing said O 2 -containing cathode effluent to said catalyst combustor; and
a cathode back pressure valve selectively applying a fluid back pressure to facilitate routing of said O 2 -containing cathode effluent to said catalyst combustor.
24. The fuel processor according to claim 15 , further comprising:
a catalyst combustor positioned in series upstream from said second combustion heater system.
25. The fuel processor according to claim 15 , further comprising:
a catalyst combustor positioned in series downstream from said second combustion heater system.
26. The fuel processor according to claim 15 , further comprising:
a catalyst combustor positioned such that an output of said catalyst combustor is input downstream of said second combustion heater system.
27. A fuel processor comprising:
a reformer converting a hydrogen-containing fuel selected from the group consisting of alcohols and hydrocarbons to H 2 -containing reformate;
a shift reactor in fluid communication with said reformer, said shift reactor being operable to reduce carbon monoxide levels of said reformate;
a preferential oxidation reactor in fluid communication with said shift reactor, said preferential oxidation reactor being operable to further reduce carbon monoxide levels of said reformats exiting said shift reactor;
a first combustion heater system coupled to said reformer, said first combustion heater system operated in a lean state to produce thermal energy as a product of internal combustion in the form of a first heated exhaust stream that is passed through said reformer; and
a second combustion heater system coupled to said shift reactor, said second combustion heater system operated in a near ideal stoichiometric condition to produce thermal energy as a product of combustion in the form of a second heated exhaust stream that is passed through said shift reactor.
28. The fuel processor according to claim 27 , wherein said second combustion heater further comprises an air inlet providing fresh air thereto.
29. The fuel processor according to claim 27 , wherein said second combustion heater system is positioned in series with said first combustion heater system.
30. The fuel processor according to claim 29 , wherein said second combustion heater further comprises a first inlet providing fresh air thereto and a second inlet in fluid communication with said first heated exhaust stream.
31. The fuel processor according to claim 30 , wherein said first heated exhaust stream is used to dilute said fresh air to control the temperature of said second heated exhaust stream.
32. The fuel processor according to claim 29 , further comprising:
a first control valve system selectively routing said first heated exhaust stream to said second combustion heater system during a startup cycle.
33. The fuel processor according to claim 27 , further comprising:
a spray vaporization zone coupled downstream from said second combustion heater system, said spray vaporization zone being operable to maintain a predetermined temperatures of said second heated exhaust stream.
34. The fuel processor according to claim 27 , further comprising;
a second control valve system selectively routing an O 2 -containing cathode effluent from a fuel cell stack to a catalyst combustor arid said second combustion heater system.
35. The fuel processor according to claim 27 , further comprising:
a catalyst combustor positioned in series upstream from said second combustion heater system.
36. The fuel processor according to claim 27 , further comprising:
a catalyst combustor positioned in series downstream from said second combustion heater system.
37. The fuel processor according to claim 27 , further comprising:
a catalyst combustor positioned such that an output of said catalyst combustor is input downstream of said second combustion heater system.