Method and apparatus for producing super clean air

摘要

Super clean air suitable for use in a tunnel-type wafer transport system, etc., is produced efficiently with the specific energy consumption reduced and the yield improved by making good use of part of cooling energy and gas produced in a low temperature separation type nitrogen producing apparatus. Material air 1a collected from the atmosphere is pretreated in a room temperature adsorption tower 7, this pretreated air is adsorption treated at -60 DEG C. in a first low temperature adsorption tower 9, and the treated air 1c is further adsorption treated at -150 DEG C. in a second low temperature adsorption tower 10, thereby producing super clean air 1e containing not higher than 1 ppb of the chemical components other than nitrogen, oxygen and noble gases and having a dew point of not higher than -100 DEG C. The airs 1b and 1c are cooled in heat exchangers 12, 13 and 14 by utilizing cooling energy produced in the low temperature separation type nitrogen producing apparatus, that is, the low temperature gas 3f passed through an expansion turbine 38 from a rectifying tower 37.