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:
Nov. 10, 1998
Filed:
May. 14, 1997
Takashi Nagamura, Kako-ken, JP;
Teisan Kabushiki Kaisha, Tokyo, JP;
Abstract
An ultra-high purity nitrogen trifluoride production method comprises: pressurizing a nitrogen trifluoride feed gas, eliminating moisture and carbon dioxide from the feed gas, and cooling down the same feed gas; causing the cooled feed gas to pass through adsorption columns, and introducing it into a medium-pressure rectification column by way of a reboiler in the medium-pressure rectification column, where it is rectified in the medium-pressure rectification column; introducing the resulting gas obtained by this rectification into a middle stage of a low-pressure rectification column, where it is rectified; and taking out ultra-high purity nitrogen trifluoride obtained by virtue of this rectification from the lower part of the low-pressure rectification column.