Dual-pressure rectification using two columns - the first having the high-pressure stage and part of the low-pressure

摘要

Dual-pressure rectification is carried out in two distillation columns placed side-by-side. The first contains the high-pressure stage and the lower portion of the low-pressure stage. The second contains the remainder of the low-pressure stage. Used for dual-pressure distn. systems for gas sepn. such as for air sepn. or crude oil distn. Economy in capital cost, is achieved, by minimising overall height, and economy in operation, by minimising liq. pumping cost.