NITROGEN PRODUCTION BY LOW ENERGY DISTILLATION

摘要

Means of producing high purity nitrogen at high recovery with lower energy requirement then has been possible heretofore. This is done with an elevated pressure dual pressure distillation column arrangement wherein the low pressure column (at about 4 ATA pressure) (component (102) in Figure 1) is reboiled by partially condensing supply air in (103) and is refluxed both by direct injection of LN2 from the HP rectifier (105) plus latent heat exchange with depressurized LP column bottom liquid in (114), and the HP rectifier is refluxed by latent heat exchange with either LP column intermediate liquid in (106) and/or depressurized kettle liquid. The basic configuration of Figure 1 involving partial condensation reboil of the LP column and intermediate LP column liquid reflux of the HP rectifier has general utility in other cryogenic separations, e.g. in nitrogen rejection units wherein N2 is separated from CH4. In that example the high N2 purity is not required, and hence the separate LP column overhead reflux condenser is not required.