Systems and processes of operating fuel cell systems
The present invention is directed to systems and processes for operating molten carbonate fuel cell systems. A process for operating the molten carbonate fuel cell includes providing a hydrogen-containing stream comprising molecular hydrogen to a molten carbonate fuel cell anode; heating a hydrocarbon stream, at least a majority of which is comprised of hydrocarbons that are liquid at 20° C. and atmospheric pressure, with a heat source comprising an anode exhaust from the molten carbonate fuel cell anode; contacting at least a portion of the heated hydrocarbon stream with a catalyst to produce a steam reforming feed comprising gaseous hydrocarbons, hydrogen, and at least one carbon oxide; separating at least a portion of the molecular hydrogen from the steam reforming feed; and providing at least a portion of the separated molecular hydrogen to the molten carbonate fuel cell anode as at least a portion of the stream comprising molecular hydrogen.
1. A process of operating a molten carbonate fuel cell, including a molten carbonate fuel cell anode, a molten carbonate fuel cell cathode, and having interposed there-between an electrolyte layer, wherein the process comprises:
providing a hydrogen-containing stream, comprising molecular hydrogen, to the molten carbonate fuel cell anode;
heating a hydrocarbon stream, at least a majority of which is comprised of hydrocarbons that are liquid at 20° C. and atmospheric pressure, with a heat source comprising an anode exhaust from the molten carbonate fuel cell anode to yield a heated hydrocarbon stream;
contacting at least a portion of the heated hydrocarbon stream with a first reforming catalyst to produce a steam reforming feed comprising hydrogen and at least one carbon oxide;
separating at least a portion of the molecular hydrogen from the steam reforming feed to provide a separated hydrogen stream and an oxidant-containing gas stream;
providing at least a portion of the separated hydrogen stream to the molten carbonate fuel cell anode as at least a portion of the hydrogen-containing stream comprising molecular hydrogen; and
providing molecular hydrogen and water to the molten carbonate fuel cell anode at a rate such that a molar ratio of water to molecular hydrogen in the anode exhaust is at most 1.0.
2. The process of claim 1 , wherein the hydrocarbon stream comprises at least one hydrocarbon having a carbon number of from 4 to 25.
3. The process of claim 1 , wherein the hydrocarbon stream comprises diesel hydrocarbons.
4. The process of claim 1 , wherein the separated hydrogen stream contains at least about 0.6 mole fraction molecular hydrogen.
5. The process of claim 1 , further comprising contacting at least a portion of the stream forming feed with a second reforming catalyst to produce a reformed product gas comprising molecular hydrogen and carbon dioxide; separating the molecular hydrogen from the reformed product gas; and providing the thus-separated molecular hydrogen to the molten carbonate fuel cell anode as at least a portion of the hydrogen-containing stream.
6. The process of claim 1 , further comprising contacting at least a portion of the stream reforming feed with a second reforming catalyst to produce a reformed product gas comprising molecular hydrogen and carbon dioxide; separating the carbon dioxide from the reformed product gas; and providing the thus-separated carbon dioxide to the molten carbonate fuel cell cathode.
7. The process of claim 1 , further comprising the steps of: passing the oxidant-containing gas stream to an oxidizing unit, the oxidant-containing gas stream comprising one or more gaseous hydrocarbons and at least one carbon oxide; contacting within the oxidizing unit at least a portion of the oxidant-containing gas stream with an oxidant to thereby produce a second hydrogen-containing stream comprising hydrogen; and providing at least a portion of the second hydrogen-containing stream to the molten carbonate fuel cell anode.
8. The process of claim 1 , wherein the molten carbonate fuel cell generates electricity at an electrical power density of at least 0.1 W/cm 2 .