Abstract: Method and apparatus for providing clean air to an environment. Incoming air, which may be contaminated with chemical, nuclear or biological contamination is initially cooled and water is removed from the cooled air by a first cooler, a first water separator, a second cooler and a second water separator. The cooled air is passed through a regenerative pressure swing absorption system which removes the contaminants. The resulting, cleaned, air is expanded by an expander. The expanded, cleaned air is provided to the environment, after being used in the second cooler to clean the incoming air.

Abstract: A method is described for providing clean air at desired temperature to an environment. Incoming air possibly contaminated with nuclear biological and chemical contaminants is compressed. The compressed air is cooled in a first heat exchanger. The cooled air from the first heat exchanger is compressed in a secondary compressor. Compressed air from the secondary compressor is cooled in a second heat exchanger. Cooled air from the secondary heat exchanger is directed through a regenerative pressure swing absorption system to provide clean output air with the contaminants removed therefrom. This cleaned air is expanded in a turbine coupled to the secondary compressor, whereby to recover energy from the cleaned air to drive the secondary compressor. The expanded cleaned air from the turbine is utilized to condition air in the environment. The regenerative pressure swing absorption system is purged with air derived from the expanded clean air.