Solid oxide fuel cell process and apparatus
Conveying gas containing sulfur through a sulfur tolerant planar solid oxide fuel cell (PSOFC) stack for sulfur scrubbing, followed by conveying the gas through a non-sulfur tolerant PSOFC stack. The sulfur tolerant PSOFC stack utilizes anode materials, such as LSV, that selectively convert H 2 S present in the fuel stream to other non-poisoning sulfur compounds. The remaining balance of gases remaining in the completely or near H 2 S-free exhaust fuel stream is then used as the fuel for the conventional PSOFC stack that is downstream of the sulfur-tolerant PSOFC. A broad range of fuels such as gasified coal, natural gas and reformed hydrocarbons are used to produce electricity.
1. A system for converting chemical energy in a fluid fuel, that contains sulfur and flows along a fuel path, to electrical energy, the system comprising:
(a) a sulfur-tolerant solid oxide fuel cell with an anode disposed in the fuel path for generating electricity and converting the sulfur-laden fluid fuel to a substantially sulfur-free fluid fuel in the fuel path downstream of the sulfur-tolerant solid oxide fuel cell; and
(b) a sulfur-intolerant solid oxide fuel cell with an anode disposed in the fuel path spaced downstream of the sulfur-tolerant solid oxide fuel cell for generating electrical energy from the substantially sulfur-free fluid fuel without substantial damage caused by sulfur.
2. The system in accordance with claim 1 , wherein the sulfur-intolerant solid oxide fuel cell oxidizes molecules in the fluid fuel that do not contain sulfur.
3. The system in accordance with claim 1 , wherein the sulfur-tolerant solid oxide fuel cell oxidizes sulfur-containing molecules in the fluid fuel.
4. The system in accordance with claim 3 , wherein the sulfur-intolerant solid oxide fuel cell anode is made of Ni and YSZ.
5. The system in accordance with claim 3 , wherein the sulfur-intolerant solid oxide fuel cell anode is made of Ni and GDC.
6. The system in accordance with claim 4 , wherein the sulfur-tolerant solid oxide fuel cell anode is made of LSV.
7. The system in accordance with claim 5 , wherein the sulfur-tolerant solid oxide fuel cell anode is made of LSV.
8. The system in accordance with claim 4 , wherein the sulfur-tolerant solid oxide fuel cell anode is made of LST.
9. The system in accordance with claim 5 , wherein the sulfur-tolerant solid oxide fuel cell anode is made of LST.
10. A method of converting chemical energy into electrical energy, the method comprising:
(a) conveying a fluid fuel containing sulfur along a fuel path in which an anode of a sulfur-tolerant solid oxide fuel cell is disposed; and then
(b) the sulfur-tolerant solid oxide fuel cell generating electricity and converting the sulfur-laden fluid fuel to a substantially sulfur-free fluid fuel in the fuel path downstream of the sulfur-tolerant solid oxide fuel cell; and then
(c) conveying the substantially sulfur-free fluid fuel downstream from the sulfur-tolerant solid oxide fuel cell along the fuel path in which an anode of a sulfur-intolerant solid oxide fuel cell is disposed; and then
(d) the sulfur-intolerant solid oxide fuel cell generating electrical energy from the substantially sulfur-free fluid fuel without substantial damage caused by sulfur.
11. The method in accordance with claim 10 , further comprising the step of the sulfur-intolerant solid oxide fuel cell oxidizing molecules in the fluid fuel that do not contain sulfur.
12. The method in accordance with claim 10 , further comprising the step of the sulfur-tolerant solid oxide fuel cell oxidizing sulfur-containing molecules in the fluid fuel.
13. The method in accordance with claim 12 , wherein the sulfur-intolerant solid oxide fuel cell anode is made of Ni and YSZ.
14. The method in accordance with claim 12 , wherein the sulfur-intolerant solid oxide fuel cell anode is made of Ni and GDC.
15. The method in accordance with claim 13 , wherein the sulfur-tolerant solid oxide fuel cell anode is made of LSV.
16. The method in accordance with claim 14 , wherein the sulfur-tolerant solid oxide fuel cell anode is made of LSV.
17. The method in accordance with claim 13 , wherein the sulfur-tolerant solid oxide fuel cell anode is made of LST.
18. The method in accordance with claim 14 , wherein the sulfur-tolerant solid oxide fuel cell anode is made of LST.
19. The method in accordance with claim 10 , further comprising the step of producing H 2 SO 4 .