US Patent 6913636 Low power nitrogen enriched air generation system

An inerting system provides air with reduced oxygen content by flowing and directing air through an air separation module. Optimal working pressure for the air separation module is obtained with two compressors. A first compressor elevates air from the aircraft cabin to a second pressure. The second pressure is at an intermediate level below the working pressure of the air separation module. A second compressor elevates air from the second pressure to the working pressure. The second compressor is driven by air that is exhausted through a turbine. The pressure difference between air at the working pressure and air required by the fuel distribution system is used to power the turbine and drive the second compressor.