A process for producing high pressure gaseous nitrogen, comprising : cooling feed air to substantially the dew-point thereof, introducing at least a portion of said air at a base of a high pressure column (107, 207); removing a oxygen enriched liquid from the base of said high pressure column; reducing the pressure of said oxygen enriched liquid to a medium pressure, wherein said medium pressure is between said high pressure and atmospheric pressure, introducing said oxygen enriched liquid at an intermediate place of a medium pressure column (106, 206); reducing the pressure of at least a part of a liquid removed from the base of said medium pressure column to a low pressure to cool a top condenser of said medium pressure column and to form a waste vapor stream; compressing a vapor stream removed from the medium pressure column in a cold compressor (105, 205), cooling said compressed vapor stream, and introducing it into the base of the high pressure column; heating said waste vapor stream, and expanding at least part of the heated waste vapor stream to produce power; withdrawing liquid from the top of said medium pressure column, pumping said withdrawn liquid to said high pressure and injecting it at the top of the high pressure column; and withdrawing product gaseous nitrogen from the top of the high pressure column.