Praxair Technology, Inc.

Sophia J Dowd

Jeremiah James Rauch

Andrew Warta

Catherine B Sarigiannis

Wei Zhang

Hao Wu

David R Parsnick

Andrew M Warta

A system and method for separating air in an air separation plant is provided. The disclosed systems and methods divert a portion of the compressed, purified air stream to a bypass system configured to selectively produce a higher pressure compressed output stream or a lower pressure compressed output stream. The higher pressure and/or lower pressure compressed output streams are cooled in a main heat exchanger by indirect heat transfer with a plurality of product streams from the air separation plant and then rectified in the distillation column system. A second portion of the compressed, purified air stream is partially cooled in the main heat exchanger and expanding in a turbo-expander to produce power and an exhaust stream which is directed to the distillation column system of the air separation plant where it imparts additional refrigeration generated by the expansion of the compressed air stream in the turbo-expander.

Air separation system and method

A method and apparatus for separating air in which production of the liquid products can be selectively varied between high and low production rates by varying the pressure ratio across a turboexpander used in imparting refrigeration with the use of a branched flow path. The branched flow path has a system of valves to selectively and gradually introduce a compressed refrigerant air stream into either a booster compressor branch having a booster compressor to increase the pressure ratio during high modes of liquid production or a bypass branch that bypasses the booster compressor to decrease the pressure ratio during low modes of liquid production. A recycle branch is connected to the booster compressor branch to allow compressed air to be independently recycled from the outlet to the inlet of the booster compressor during turndown from the high to the low liquid mode of liquid production to prevent surge.

Air separation apparatus

Air separation method and apparatus

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.

Method and system for air separation using a supplemental refrigeration cycle

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Grand Island, NY, United States of America

Sophia J Dowd