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:
Sep. 15, 1992
Filed:
Jul. 11, 1991
John T Lavin, Guildford, GB;
The BOC Group plc, Surrey, GB;
Abstract
An air stream is compressed in a compressor, and purified in an apparatus. A major portion of the compressed, purified air stream is then cooled in a main heat exchanger to a temperature suitable for its separation in a double rectification column comprising a higher pressure column and a lower pressure column. The lower pressure column typically operates at a pressure in the range of 2.5 to 4.5 bar. A minor portion of the compressed, purified air stream is employed to generate refrigeration for the air separation by being further compressed in the compressor and expanded in a turbine. Oxygen and nitrogen product streams are withdrawn from the lower pressure column. The nitrogen product stream is passed through the main heat exchanger countercurrently to the major air stream. A part of this nitrogen stream is withdrawn at an intermediate region of the heat exchanger and is expanded in an expansion turbine. The resulting expanded nitrogen passes through the heat exchanger from its cold to its warm end thereby creating additional refrigeration so as to maintain a mean temperature different from end to end of the heat exchanger of at least 10K between the streams being warmed and the streams being cooled. A substantial reduction in the size of the heat exchanger compared with that of a conventional plant thereby becomes possible. The expanded nitrogen stream leaving the warm end of the heat exchanger may also be used to perform a cooling duty at about ambient temperature.