Patent ID: 6332337
Filing Date: 2001-12-25
Classification: F25J

Abstract:
A method for recovering oxygen at hyperbaric pressure by low-temperature air fractionation in a rectifying system that comprises a pressure column and a low-pressure column, said method comprising:compressing feed air to a first pressure that is approximately equal to an operating pressure of the pressure column;cooling at least a first partial flow of the feed air compressed to the first pressure in a main heat exchanger;passing the cooled first partial flow into the pressure column;work-expanding the pressure of a process stream from the main heat exchanger and supplying the process stream to the low-pressure column, wherein at least a portion of the mechanical energy generated by the work-expanding of the process stream drives a cold compressor;tapping a liquid oxygen flow from the low-pressure column;bringing the liquid oxygen flow to a delivery pressure that is higher than the operating pressure of the low-pressure column;evaporating the liquid oxygen flow by indirect heat exchange with a second partial flow of the feed air compressed to the first pressure which is brought to a second pressure by the cold compressor;heating the evaporated oxygen flow in the main heat exchanger; anddischarging the heated oxygen flow.