Fuel mixing control for fuel cell power plants operating on multiple fuels

摘要

Fuel mixing control arrangements are provided for fuel cell power plants ( 10 ) operating on multiple fuels ( 22, 24, 26 ). A fuel delivery system ( 16 ) supplies hydrogen-rich fuel ( 20 ) to the cell stack assembly (CSA) ( 12 ) after controlled mixing of a primary fuel ( 22 ) and at least a secondary fuel ( 24 ), each having a respective "equivalent hydrogen (HSUB2/SUB) content". The relative amounts of the primary fuel ( 22 ) and secondary fuel ( 24 ) mixed are regulated ( 18, 34, 36 ) to provide at least a minimum level (LL) of hydrogen-rich fuel having an equivalent hydrogen content sufficient for normal operation of the CSA ( 12 ). The primary fuel ( 22 ) is a bio-gas or the like having a limited, possibly variable, equivalent HSUB2 /SUBcontent, and the secondary fuel ( 22 ) has a greater and relatively constant equivalent H2 content and is mixed with the primary fuel in an economic, constant relationship that assures adequate performance of the CSA ( 12 ). One or more parameters (IDC, P, V, E. C.) of the operating power plant ( 10 ) related to the equivalent HSUB2 /SUBcontent of at least the primary fuel may be sensed ( 72, 26, 78, 84, 176 ) and used to control ( 18, 36 ) the relative amounts of secondary and primary fuels ( 22, 24 ) mixed in response thereto.