Nitrogen generator with waste distillation and recycle of waste distillation overhead

Abstract From the Canadian patent

The present invention is an improvement to a standard nitrogen generator. The improvement is two-fold; first the addition of one or, more distillation stages above the reboiler which stages effectively, transform the reboiler/condenser into a partial low pressure column and allow further separation (rectification) of the nitrogen generator bottoms liquid into two streams. Second the recycle of the overhead, stream (at a composition close to that of air) from the top of the low pressure column to the main air compressor. Additionally at least a, portion of the oxygen-enriched stream that exits the low pressure column below the bottom tray is expanded to provide refrigeration for the cycle.