Air separation process with modified single distillation column nitrogen generator

Claim 1

In a nitrogen generator air separation process which utilizes a cryogenic single distillation column nitrogen (nitrogen generator) and either a waste expander or an air expander for the provision of refrigeration, wherein the cryogenic single distillation column has an overhead condenser and a sump surrounding the overhead condenser, the improvement for producing a high purity oxygen co-product comprising: (a) integrating a secondary distillation column into the process; (b) removing a portion of oxygen-rich liquid from the sump of the nitrogen generator column overhead condenser and feeding said oxygen-rich liquid to an upper location of the secondary distillation column; (c) providing reboil for the secondary distillation column by condensing a portion of nitrogen overhead from the nitrogen generator column in a reboiler/condenser located in the bottom of the secondary distillation column; (d) utilizing at least a portion of the condensed nitrogen liquid from the reboiler/condenser located in the bottom of the secondary distillation column to provide reflux to the nitrogen generator column; and (e) recovering the high purity oxygen co-product from the secondary distillation column; whereby the high purity oxygen co-product is recovered from a waste stream normally vented to the atmosphere in the nitrogen generator process and is accomplished without additional operating power or air feed requirements.