US 12,305,916 B2
Method to convert excess liquid oxygen into liquid nitrogen
Adam Histed, Lafayette Hill, PA (US); and Paul Sweeney, King of Prussia, PA (US)
Assigned to Airgas, Inc., Radnor, PA (US)
Filed by Airgas, Inc., Radnor, PA (US)
Filed on Oct. 6, 2021, as Appl. No. 17/495,385.
Claims priority of provisional application 63/089,578, filed on Oct. 9, 2020.
Prior Publication US 2022/0112083 A1, Apr. 14, 2022
Int. Cl. F25J 3/04 (2006.01); C01B 21/02 (2006.01); C01B 21/04 (2006.01); F25J 1/00 (2006.01)
CPC F25J 1/0015 (2013.01) [C01B 21/02 (2013.01); F25J 1/004 (2013.01); F25J 3/0406 (2013.01); F25J 3/04224 (2013.01); F25J 3/04503 (2013.01); F25J 2230/42 (2013.01); F25J 2250/42 (2013.01); F25J 2250/50 (2013.01)] 8 Claims
OG exemplary drawing
 
1. A method for exchanging heat between an excess liquid oxygen stream with a gaseous nitrogen stream to produce an additional liquid nitrogen stream, comprising:
introducing a gaseous nitrogen stream into a main heat exchanger, therein indirectly exchanging heat with a vaporized oxygen stream, a vapor phase nitrogen steam, and a waste liquid nitrogen stream; thereby producing a cold gaseous nitrogen stream, a warm oxygen vent stream, a warm nitrogen vent steam, and a warm gaseous nitrogen waste stream,
introducing the cold gaseous nitrogen stream into a secondary heat exchanger, therein indirectly exchanging heat with a liquid oxygen stream; thereby producing the vaporized oxygen stream and a cold liquid nitrogen stream,
introducing the cold liquid nitrogen stream into a nitrogen pressure reduction valve thereby producing a two-phase nitrogen stream,
introducing the two-phase nitrogen stream into a nitrogen flash vessel thereby producing a liquid phase nitrogen stream and the vapor phase nitrogen stream,
wherein the method is performed in the absence of refrigerant turbo-expanders, refrigerant expansion turbines, or refrigerant compressors.