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 (H₂) 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 H₂ content, 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 H₂ content 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.