AIR SEPARATION PLANT WITH EXCESSIVE RETURN STREAM

Abstract

Increasing energy costs makes it necessary to search for new ways to reduce energy consumption of air separation plants. Current practice of refrigerating capacity control of medium pressure air separation plants comes down to decreasing the fraction of air, which expands in the expander, and increasing the air flow passing through the expansion valve. This is equivalent to introducing additional thermodynamic losses in the cycle of a cryogenic plant. As an alternative to the current practice, we suggest operating air separation plant in the mode of maximum exergy efficiency accumulating exergy as bottoms liquid. After accumulating bottoms liquid, the plant works is the decreased energy consumption mode and the accumulated bottoms liquid is utilized to compensate for cold losses in the plant. This method of operating the air separation plant will allow reducing energy consumption in the production of gaseous oxygen by about 40% compared to the existing medium pressure plants.