Abstract: A system for re-starting an air separation plant after an interruption in operation wherein descending liquid is collected in a non-operating distillation column and passed back to the separation section of that column before or upon re-start. The invention may employ a collection device situated in the column above the sump. Upon interruption in operation, the collection device accumulates descending liquid. From the collection device, liquid may be passed outside of the column and transferred to a holding vessel to re-inventory internal material of the column upon resumption in operation.

Abstract: A cryogenic rectification system wherein liquid oxygen from a cryogenic air separation plant is pressurized and then vaporized in a high pressure liquefier producing product high pressure oxygen gas and generating liquid nitrogen for enhanced liquid product production.

Abstract: A low temperature refrigeration process wherein a feed gas mixture comprising hydrogen or helium as major component and a minor component with normal boiling point above 170.degree. K and molecular weight of at least 28 is dynamically compressed at higher temperature and cooled to intermediate temperature for condensation and separation of the minor component. Pure major component is further cooled and work expanded at lower temperature and recycled for mixing with the condensed minor component during rewarming to form at least the major fraction of the feed gas mixture.