Process and apparatus for producing high-purity nitrogen by low-temperature fractionation of air

US6708523B2 · kind B2 · utility

Assignee

• Linde GmbH · DE

Inventors

• Stefan Lochner · Grafing, DE
• Ralph Spöri · Öhnböck, DE
• Michael Lauter · Mannheim, DE

Key dates

• Filing date: Oct 4, 2002
• Grant date: Mar 23, 2004
• Expiry date: Oct 4, 2022

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S62/912
• WIPO field: Chemical engineering
• WIPO sector: Chemistry

Abstract

The invention relates to a process and apparatus for producing nitrogen by low-temperature fractionation of air in a rectification system which has a high-pressure column (4) and a low-pressure column (5). Feed air (1, 3) is introduced into the high-pressure column (4). An oxygen-containing liquid fraction (11) is removed from the high-pressure column (4) and fed into the low-pressure column (5). Gaseous nitrogen (18) is extracted from the low-pressure column (5) above a mass transfer section (25), which has at least one theoretical or practical plate, and is at least partially condensed in a top condenser (17) by indirect heat exchange with a refrigerant (13). High-purity nitrogen is removed from the low-pressure column below the mass transfer section (25), and is obtained as a nitrogen product (26, 27, 30). The process and apparatus have a refrigeration-supply system, in which a refrigeration fluid (31) flows. At least part of the refrigeration fluid from the refrigeration-supply system is introduced into the low-pressure column (5) above the mass transfer section (25).