Separation of air utilizing a closed-cycle helium refrigeration system

Abstract

Abstract IN THE SEPARATION OF OXYGEN AND NITRONGEN FROM AIR, THE PROCESS INVOLVING INTRODUCING COMPRESSED COOLED AIR AT ITS SATURATION TEMPERATURE INTO A FRACTIONATING COLUMN, PASSING ANOTHER GASEOUS MEDIUM SUCH AS HELIUM INTO HEAT EXCHANGE RELATION ALONG THE LOWER PORTION OF THE FRACTIONATING COLUMN, THE HELIUM BEING AT A TEMPERATURE TO SUPPLY HEAT ALONG THE LOWER PORTION OF THE COLUMN, COOLING THE RESULTING HEATED HELIUM, PREFERABLY BY HEAT EXCHANGE WITH AN EXTERNAL REFRIGERANT FOLLOWED BY WORK EXPANSION OF THE HELIUM, PASSING THE COOLED HELIUM GAS INTO HEAT EXCHANGE RELATION ALONG THE UPPER PORTION OF THE COLUMN, SUCH HELIUM BEING AT A TEMPERATURE TO REMOVE HEAT ALONG THE UPPER PORTION OF THE COLUMN, COMPRESSING THE EXCITING HELIUM AND RECYCLING SAME IN HEAT EXCHANGE RELATION ALONG THE LOWER PORTION OF THE COLUMN THUS EFFECTING A DIFFERENTIAL DISTILLATION OF THE AIR IN THE COLUMN AND SEPARATING NITROGEN OVERHEAD FROM THE UPPER END OF THE COLUMN AND LIQUID OXYGEN FROM THE LOWER END OF THE COLUMN. IN THE PREFERRED PROCEDURE, NITROGEN OVERHEAD IS PASSED IN HEAT EXCHANGE RELATION WITH COMPRESSED FEED AIR FOR COOLING SAME, A PORTION OF THE HEATED NITROGEN GAS IS COMPRESSED AND COOLED, AND SUCH COOL COMPRESSED NITROGEN PASSED IN HEAT EXCHANGE RELATION WITH LIQUID OXYGEN WITHDRAWN FROM THE BOTTOM OF THE COLUMN, COOLING THE COMPRESSED NITROGEN AND VAPORIZING THE OXYGEN, WHICH IS WITHDRAWN AS PRODUCT, THE COOLED NITROGEN IS PASSED IN HEAT EXCHANGE RELATION WITH THE LOWER PORTION OF THE COLUMN, IS SUBCOOLED BY HEAT EXCHANGE RELATION WITH NITROGEN OVERHEAD WITHDRAWN FROM THE COLUMN, IS THROTTLED, AND THE RESULTING NITROGEN INTRODUCED AS REFLUX TO THE TOP OF THE COLUMN. THE SYSTEM HAS THE ADVANTAGE OF EMPLOYING A SINGLE FRACTIONATING COLUMN OPERATING AT OR SLIGHTLY ABOVE ATMOSPHERIC PRESSURE, WITH REDUCED POWER CONSUMPTION AND INCREASED EFFICIENCY, THE ONLY GAS REQUIRING SIGNIFICANT COMPRESSION BEING THE PORTION OF THE GASEOUS NITROGEN WITHDRAWN FROM THE UPPER END OF THE COLUMN AND RECYCLED TO PROVIDE ADDITIONAL REFLUX TO THE COLUMN.

Inventors

• 👤 James D Yearout

Bibliographic Details