A pre-reformer ( 10 ) comprises a non-electrically conducting gas tight duct ( 12 ) and an electrically conducting wire ( 14 ) arranged in the duct ( 12 ). The electrically conducting wire ( 14 ) is electrically isolated from the duct ( 12 ). The duct ( 12 ) has an inlet ( 16 ) for receiving a hydrocarbon fuel at a first end ( 18 ) and an outlet ( 20 ) for supplying a pre-reformed hydrocarbon fuel at a second end ( 22 ). At least the inner surface ( 24 ) of the duct ( 12 ) is chemically inert with respect to the hydrocarbon fuel. An electrical power supply ( 26 ) is electrically connected to the electrically conducting wire ( 14 ) and a control means ( 28 ) controls the supply of electrical current through the electrically conducting wire ( 14 ) to maintain the electrically conducting wire ( 14 ) at a temperature to provide selective thermal decomposition of higher hydrocarbons in the hydrocarbon fuel. The performer reduces coking in associated fuel cells and other parts of a fuel cell system.
1. A pre-reformer comprising:
a gas tight duct,
at least one electrically conducting member arranged in the duct, the at least one electrically conducting member is electrically isolated from the duct,
the duct has an inlet for receiving a hydrocarbon fuel at a first end and an outlet for supplying a pre-reformed hydrocarbon fuel at a second end, the duct being adapted to receive only hydrocarbon fuel,
at least the inner surface of the duct is chemically inert with respect to the hydrocarbon fuel,
an electrical power supply electrically connected to the at least one electrically conducting member, and
control means to control the supply of electrical current through the at least one electrically conducting member to maintain the at least one electrically conducting member at a temperature to provide selective thermal decomposition of higher hydrocarbons in the hydrocarbon fuel.
2. A pre-reformer as claimed in claim 1 wherein the gas tight duct is non-electrically conducting.
3. A pre-reformer as claimed in claim 1 wherein the gas tight duct comprises a ceramic, a glass-ceramic or a glass.
4. A pre-reformer as claimed in claim 1 wherein a temperature sensor is arranged to measure the temperature in the duct and is electrically connected to the control means.
5. A pre-reformer as claimed in claim 1 wherein the at least one electrically conducting member extends through the walls of the duct and is directly electrically connected to the electrical power supply.
6. A pre-reformer as claimed in claim 5 wherein the electrically conducting member is electrically isolated from the duct by glass seals or glass-ceramic seals.
7. A pre-reformer as claimed in claim 1 wherein the at least one electrically conducting member forms a loop, a second electrically conducting member is arranged outside the duct, the second electrically conducting member is electrically connected to the electrical power supply and the control means controls the supply of electrical current through the second electrically conducting member to maintain the at least one electrically conducting member at a temperature to provide selective thermal decomposition of higher hydrocarbons in the hydrocarbon fuel.
8. A pre-reformer as claimed in claim 1 wherein the at least one electrically conducting member comprises a honeycomb.
9. A pre-reformer as claimed in claim 1 wherein the at least one electrically conducting member comprises at least a portion of the duct.
10. A pre-reformer as claimed in claim 1 wherein the at least one electrically conducting member comprises a metal or an alloy.
11. A pre-former according to claim 1 , wherein the hydrocarbon fuel is natural gas.