Combustion turbine and elevated pressure air separation system with argon recovery

In a process for the generation of power in an integrated gasification combined cycle power generation system, wherein a compressed air feed is separated in a cryogenic distillation system at elevated pressure to recover oxygen and nitrogen, at least a portion of the oxygen is used in the gasification of a carbonaceous feedstock to provide a combustible gas mixture, and at least a portion of the gas mixture is combusted with compressed combustion air in a gas turbine combustor to generate hot pressurized gas which is expanded in a gas turbine which drives an electric generator to generate electric power, the improvement which comprises recovering an argon product in combination with the recovery of oxygen and nitrogen, wherein the compressed air feed for the cryogenic distillation system and the compressed combustion air for the gas turbine combustor are supplied by separate compression steps, and wherein the oxygen, nitrogen, and the argon product are recovered in a multiple column distillation process which comprises:

• a) cooling the compressed air feed and separating the resulting cooled feed in a higher pressure column to yield a bottoms stream enriched in oxygen and argon;
• b) cooling the bottoms stream, reducing the pressure of the resulting cooled stream, and introducing the resulting cooled reduced pressure stream into a lower pressure column;
• c) withdrawing a high purity oxygen product which contains greater than 98 vol % oxygen from the bottom of the lower pressure column and an argon-enriched vapor from an intermediate point in the lower pressure column;
• and
• d) introducing the argon-enriched vapor into an argon recovery distillation column, withdrawing and condensing a further argon-enriched overhead vapor therefrom, utilizing a portion of the resulting condensate as reflux for the column, and withdrawing the remaining portion of the condensate as an enriched argon product;
• wherein boilup in the lower pressure column is provided in total by indirect heat exchange with vapor from the higher pressure column, and wherein feed to the higher pressure column is provided from the cooled feed of step a) without additional compressed vapor recycled from other points in the multiple column distillation process.