Integrated production of ammonia and urea

US4690812A · kind A · utility

Assignee

• Linde GmbH · DE

Inventors

• Gerhard Ranke · Pöcking, DE
• Ulrich Schrader · Germersheim, DE

Key dates

• Filing date: Jan 18, 1985
• Grant date: Sep 1, 1987
• Expiry date: Jan 18, 2005

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y02C20/40
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

The combined production of ammonia and urea by the reaction of gases containing hydrocarbons with steam is conducted by using a steam reformer, downstream secondary reformer, and shift converter. The ammonia synthesis gas (hydrogen, nitrogen and carbon dioxide) is subjected to a high pressure scrubbing step with a physical solvent, to remove the acid impurities, especially CO.sub.2. The pressure on the loaded solvent is reduced to a first intermediate pressure for degasing of the coabsorbed inerts and then to a second intermediate pressure for removal of the bulk of the absorbed CO.sub.2, which is then used for urea synthesis. To remove residual CO.sub.2, the solvent is stripped with air and the resultant air stream containing the stripped residual CO.sub.2 is fed to the secondary reformer.