Nitrogen rejection method and apparatus
US6584803B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Jul 10, 2002 |
| Grant date | Jul 1, 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 rectified in a double rectification column comprising a higher pressure column, a lower pressure column and a condenser-reboiler placing the higher and lower pressure rectification columns in heat exchange relationship with each other. At least part of the feed gas stream is expanded through a valve into the higher pressure rectification column and the feed gas stream is partially liquefied upstream of the double rectification column. Over a period of time, the mole fraction of nitrogen in the feed gas stream may increase. The operating pressure of the lower pressure rectification column is periodically increased in response to increases in the mole fraction of nitrogen. A back pressure valve may be periodically adjusted to effect the increase in pressure.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.