Nitrogen rejection method and apparatus
US6637239B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Jul 10, 2002 |
| Grant date | Oct 28, 2003 |
| Priority date | — |
| Expiry date | Jul 10, 2022 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S62/927
- WIPO fieldChemical engineering
- WIPO sectorChemistry
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.