Experimental evaluation of the performance of a cryogenic distillation system under offshore conditions

Abstract

Cryogenic distillation is the most widely-used industrial method to produce liquid oxygen with high-purity. However, the distillation process in the sieve tray column is very sensitive to tilting and swing, which limits the application of cryogenic air-separation in marine and offshore infrastructures. In this paper, a small air-separation plant with dual-column distillation process was proposed to improve the distillation performance under the offshore conditions, and experiments were carried out under standard (no-tilting and stationary), tilting and swing conditions. A reduction factor of overall section efficiency is proposed to evaluate the influence of offshore conditions on the system performance. The results indicate that sieve tray column can maintain the distillation purity to a certain extent under offshore conditions within the range of 6° tilting and ±10° swing amplitude. Under severe tilting (6°) and swing (±10°-amplitude&11 s-period) conditions, the reduction factors were reduced to 0.592 and 0.590, respectively. Based on the experimental results, two correlations are presented to predict the reduction factor of section efficiency under different tilting angle and swing parameters, respectively, which provide engineering guidance for the design of cryogenic distillation column for offshore applications.