Development of a distillation column for a dual-mode LOX-LIN plant at BARC

A dual-mode air separation plant producing either liquid oxygen (LOX) or liquid nitrogen (LIN) using a common single distillation (rectification) column for both the LOX and LIN modes, is conceptualized by BARC. The present work describes the sizing & optimization of a packed bed distillation column for LOX & LIN modes of operation. The basic calculation of the number of theoretical stages is a precursor to a more detailed analysis of a packed bed column using the HETP & HTU-NTU methods employing correlations for mass transfer coefficients. The results from the cryogenic process calculations act as inputs for the design of the column. A single, optimized column catering to all possible modes of operation provides flexibility and compactness, increases plant availability and at the same time reduces capital cost.