Method and system for air separation using a supplemental refrigeration cycle

Abstract

A system and method for air separation using a supplemental refrigeration cycle is provided. A portion of the refrigeration required by the air separation plant to produce a liquid product stream is supplied via a supplemental refrigeration circuit configured to direct a cooled refrigerant produced by the turboexpander through the main heat exchanger of the air separation plant. The refrigeration capacity is controlled by removing or adding a portion of the refrigerant in the supplemental refrigeration circuit to adjust the inlet pressure while maintaining a substantially constant volumetric flow rate and substantially constant pressure ratio across the compressor. Removing the refrigerant from the supplemental refrigeration circuit decreases the refrigeration imparted by the supplemental refrigeration circuit and thus decreases the production of the liquid product stream. Adding refrigerant allows for an increase in the refrigeration imparted by the supplemental refrigeration circuit and thus allows for increased production of the liquid product stream.