The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 28, 2003
Filed:
Jul. 10, 2002
John Douglas Oakey, Godalming, GB;
The BOC Group plc, Windlesham, GB;
Abstract
Nitrogen is rejected from a feed gas stream comprising methane and nitrogen so as to form a methane product. The feed gas stream is cooled in a main heat exchanger and is rectified in a double rectification column comprising a higher pressure rectification column, a lower pressure rectification column, and a condenser-reboiler placing the higher pressure rectification column in heat exchange relationship with the lower pressure rectification column. At least part of the feed gas stream is expanded into the higher pressure rectification column through an expansion valve, the feed gas stream being partially liquefied upstream of the double rectification column. Over a period of time the mole fraction of nitrogen in the feed gas mixture increases. At a suitable increased nitrogen mole fraction, operation of a second double rectification column in parallel with the first double rectification column is commenced.