Note is added here to acknowledge the pioneering work by Westinghouse in the unique application of a W201 installed at U.S. Steel works in Chicago (1960). The engine was used to drive a 12,500 scfm fan to blow air into a blast furnace, and the design requirement was to use blast furnace exhaust gas as its fuel. The engine was modified so that all compressor discharge could be removed and fed to an external burner, from which products of combustion were returned to drive the turbine. Typically, blast furnace gas has a heating value of less than 100 Btu/scf, one-tenth of that of natural gas.