Abstract: An air separation process wherein a nitrogen enriched fraction is withdrawn from the distillation column, a portion of which is compressed and recycled through the lowest positioned reboiler in the column and directed to an upper portion of the column as reflux.

Abstract: A process for producing gaseous nitrogen from a mixture to be treated in a distillation column, said mixture comprising nitrogen and oxygen, said process comprising the steps of:a) compressing the mixture to be treated to a pressure at least equal to the column pressure;b) cooling the compressed gas mixture and subjecting at least a first portion of said cooled mixture to expansion through a turbine to produce the required refrigeration and thereafter fractionated distillation in the column to obtain at the bottom of the column, an oxygen-enriched fraction and, at the top of the column, a nitrogen-enriched fraction,c) drawing off at least a portion of the nitrogen-enriched fraction as nitrogen product;d) compressing the remaining portion of the nitrogen-enriched fraction;e) recycling at least a portion of the compressed remaining portion of the nitrogen-enriched fraction to the bottom reboiler of the column where it condenses to provide reboil for the column;f) introducing at least a portion of the condensed

Abstract: According to this process, compressed air is cooled and purified by adsorption by passing same in a first direction through a mass of adsorbent material (8), then a residual gas from the distillation apparatus passes in opposite direction through this mass to regenerate same. During the entire regeneration, the residual gas is at a constant regeneration temperature which is between the temperature of the air entering into the mass of adsorbent material and at a temperature which is about 50.degree. C. above this temperature.