Process and plant for the production of urea

US5276183A · kind A · utility

Assignee

• Urea Casale SA · CH

Inventors

• Giorgio Pagani · Milano, IT
• Umberto Zardi · Lugano, CH

Key dates

• Filing date: Jan 24, 1992
• Grant date: Jan 4, 1994
• Expiry date: Jan 24, 2012

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y02P20/582
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

Process for the industrial synthesis of urea, in which ammonia (NH3) and carbon dioxide (CO2) are reacted in at least one reaction space SR at high temperature and pressure and the unreacted materials are treated in a recovery section, said synthesis comprising: a) a reaction between highly pure reagents; and b) a reaction between less pure reagents substantially recycled from said recovery section, characterized by the fact that reaction stage A for high Yield majority synthesis (HEPC), between very pure reagents, operating at a higher pressure (Pmax) for example above 300 kg/cm2 abs and preferably at about 400 kg/cm2 abs, is followed by a flash stage F1 operating at pressures lower by at least 40% than said pressure (Pmax) preferably lower than 200 kg/cm2 abs, the gas effluent GF1 from the above-mentioned flash stage F1 being fed to reaction stage B for minority synthesis of less pure reagents operating at a pressure below 200 kg/cm2 abs, while the liquid effluent EL1 from the abovementioned flash stage, together with effluent EB from stage B of minority reaction operating in parallel with majority reaction stage A, feeds a recovery section RE consisting of two decomposition stag…