Separation of nitrogen from methane

• US 2,823,523 A
• Filed: 03/26/1956
• Issued: 02/18/1958
• Est. Priority Date: 03/26/1956
• Status: Expired due to Term

• Current Assignee: Bert E. Eakin, Rex T. Ellington
• Original Assignee: Bert E. Eakin, Rex T. Ellington
• Inventors: Eakin, Bert E., Ellington, Rex T.
• Application Number:
  US03/573,865
• Time in Patent Office: 694 Days
• US Class Current: 62/622
• CPC Class Codes: F25J 2200/02 in a single pressure main column system
• CPC Class Codes: F25J 2200/50 using multiple (re-)boiler-condensers at different heights of the column
• CPC Class Codes: F25J 2200/74 Refluxing the column with at least a part of the partially condensed overhead gas
• CPC Class Codes: F25J 2210/06 Splitting of the feed stream, e.g. for treating or cooling in different ways
• CPC Class Codes: F25J 2240/02 Expansion of a process fluid in a work-extracting turbine (i.e. isentropic expansion), e.g. of the feed stream
• CPC Class Codes: F25J 2240/12 the fluid being nitrogen
• CPC Class Codes: F25J 2240/30 Dynamic liquid or hydraulic expansion with extraction of work, e.g. single phase or two-phase turbine
• CPC Class Codes: F25J 2270/02 Internal refrigeration with liquid vaporising loop
• CPC Class Codes: F25J 2270/08 Internal refrigeration by flash gas recovery loop
• CPC Class Codes: F25J 2270/12 External refrigeration with liquid vaporising loop
• CPC Class Codes: F25J 2270/60 Closed external refrigeration cycle with single component refrigerant [SCR], e.g. C1-, C2- or C3-hydrocarbons
• CPC Class Codes: F25J 3/0209 Natural gas or substitute natural gas
• CPC Class Codes: F25J 3/0233 separation of CnHm with 1 carbon atom or more
• CPC Class Codes: F25J 3/0257 separation of nitrogen from air F25J3/04, production of nitrogen in general C01B21/00
• CPC Class Codes: Y10S 62/927 Natural gas from nitrogen

Claims

1. IN A PROCESS FOR SEPARATING NITROGEN FROM A GASEOUS MIXTURE OF METHANE AND NITROGEN BY LIQUEFACTION AND FRACTIONAL DISTILLATION IN A DISTILLATION COLUMN MAINTAINED AT ELEVATED PRESSURE, THE STEPS OF COMPRESSING METHANE REFRIGERANT GAS TO ABOVE SAID ELEVATED PRESSURE, PASSING THE COMPRESSED METHANE SEQUENTIALLY THROUGH A VAPORIZER CONTAINING COLD PRODUCT METHANE FROM THE DISTILLATION COLUMN TO VAPORIZE THE PRODUCT METHANE AND THROUGH COLD PRODUCT METHANE IN THE LOWER REBOILER PORTION OF THE DISTILLATION COLUMN TO SUPPLY HEAT FOR OPERATING THE COLUMN, THEREBY SIMULTANEOUSLY REDUCING THE TEMPERATURE OF THE COMPRESSED METHANE TO CONDENSE SAID COMPRESSED METHANE, FIRSTLY PARTIALLY EXPANDING SAID CONDENSED METHANE TO A GAS AND A LIQUID PHASE AT ABOUT ONEHALF SAID ELEVATED PRESSURE, PASSING THE GAS PHASE AND PORTION OF THE LIQUID PHASE THROUGH A HEAT EXCHANGER TO SUPPLY PART OF THE REFRIGERATION REQUIRED TO CONDENSE THE FEED GAS, SECONDLY FURTHER EXPANDING THE REMAINDER OF THE LIQUID PHASE TO A MIXTURE OF GAS AND LIQUID AT ABOUT ONE-FOURTH SAID ELEVATED PRESSURE, PASSING THE GAS AND MOST OF THE LIQUID AT SAID REDUCED PRESSURE THROUGH A SECOND HEAT EXCHANGER TO SUPPLY REFRIGERATION FOR SUBCOOLING SAID CONDENSED FEED GAS BEFORE INTRODUCTION INTO THE DISTILLATION COLUMN, AND FINALLY EXPANDING THE REMAINING LIQUID FROM SAID REDUCED PRESSURE TO SUBSTANTIALLY ATMOSPHERIC PRESSURE TO PROVIDE REFRIGERATION FOR A REFLUX CONDENSER CONNECTED TO SAID DISTILLATION COLUMN.