Process and apparatus for the production of moderate purity oxygen

A cryogenic process for production of an oxygen product from air, wherein the air is compressed, purified to remove contaminants which freeze out at cryogenic temperatures and cooled to near its dew point, wherein the cooled, purified, compressed air is fed to a separator, wherein separator vapor is rectified into a nitrogen-enriched rectifier overhead and a crude liquid oxygen bottoms;

• wherein an oxygen-enriched liquid is stripped to produce a nitrogen-enriched stripper overhead and the oxygen product, characterized in that a multiple passage plate-fin heat exchanger having at least two sets of passages is used to effectuate the rectifying and stripping functions, wherein one set of passages comprises a continuous-contact rectification dephlegmator which rectifies the separator vapor and produces the enriched-nitrogen rectifier overhead and the crude liquid oxygen bottoms;
• wherein a second set of passages comprises a continuous-contact stripping dephlegmator which strips the oxygen-enriched liquid to produce the nitrogen-enriched stripper overhead and the oxygen product;
• wherein reflux of the rectification device and boilup for the stripping device is provided, at least in part, by indirect heat exchange between and along said two sets of passages, thereby producing a thermal link between the rectification dephlegmator and the stripping dephlegmator.